INTRODUCTION

 

    One of the most terrifying thoughts in this 20^th century is the thought of getting cancer. Cancer has become synonymous here in the United States, with a slow, painful, certain death.  Although many advances have been made, the first thought that enters the mind when the word cancer is heard is that life is over.       Technological advances have been made in almost every aspect of cancer research and treatment.  New monoclonal antibodies have been developed, allowing a lethal dose of “medication” to be delivered to the tumor site, reducing collateral damage to the patient. New technologies have also been developed that improve the design and function of simulators, treatment machines, and the sophisticated computers and programs that calculate dose distribution. New developments with CTs and MRI allow three-dimensional conformal treatment planning to be a reality of the 1990s.

    In many ways, patient positioning is the last frontier of proper treatment planning. Some hospitals will spend millions of dollars on the latest digital 3-D imaging and treatment equipment, only to use tape or pillows to position their patient. Oftentimes, I have visited hospitals that actually use equipment and supplies from the local hardware store to create a repositioning aid for their patients. Patients have been taped, skewered and plastered into positions by the medical professionals to whom they have entrusted their lives. Many medical facilities simply refuse to see the importance that repositioning plays in proper radiation therapy treatment planning. 

    This field guide has been put together to promote ideas and discussions regarding the proper use of customized repositioning devices. Any facility that uses positioning guides in place of repositioning guides is cheating their patients of the best chance for treating and hopefully eliminating cancer from their bodies. Current literature is replete with study after study showing the importance of repositioning devices. The correct use of immobilization devices will improve treatment accuracy, improve and heighten the comfort level of the patient, helping to maximize the dose to the tumor while reducing collateral damage to surrounding tissues. This collateral damage is the clean medical way to say sometimes delivering extremely high doses of radiation to the heart or spinal cord, or other significant organ. It can be lost on the medical professional who is merely planning dose calculations that by not positioning the patient in the same position for each treatment, that the patient is receiving 10-30 treatments in different positions. Calculations are based on assuming the target is the same for each of the treatments. However, if the patient moves just half a centimeter for each treatment, the effect can be a shotgun approach to patient treatment…a radiation shotgun.

    Proper patient positioning is perhaps the most critical element that 100% under the complete control of the medical professional.  There have been significant improvements over the years that provide the medical field with easy-to-use tools to help keep their patients in the correct se-up position for each treatment.  In this field guide, you will find studies from hospital all across the United States, and outside the United States, that show how customized repositioning devices have been used to improve the accuracy of treatment and the comfort of their patients.

    Since 1981, ALPHA CRADLE^® brand repositioning devices have been used to improve the accuracy of treatment and increase patient comfort, while providing a reproducible patient set-up. The product line started with the thorax form and head and shoulder form, and developed to the current line today that includes over 40 different anatomical forms. The ALPHA CRADLE^® brand customized repositioning forms have been successfully used in 15 different countries around the world. Each year, tens of thousands of patients are treated using the ALPHA CRADLE^® brand repositioning devices.  Each device is guaranteed free from defect with a free replacement guarantee.  Smithers Medical Products, Inc. has also implemented a safety and education program that has been designed to insure that the user has adequate knowledge of the safe, correct and proper use of the product before it is used on a patient. The safety and education program comes with a detailed step-by-step manual that shows the correct use of the product, an illustrated instruction sheet, a detailed video showing the use of our prefabricated ALPHA CRADLE^® brand forms, our newer hands-on ALPHA CRADLE^® Mold Maker II that allows the medical professional to create the type of form needed, and our latest development, the Bravelle™, a single breast immobilizer, as well as assorted safety wear for the user and a protective hair bonnet for the patient. 

    Current literature references “ALPHA CRADLES^®” and their effective use in proper patient positioning. Information on ALPHA CRADLE^® brand patient repositioning systems can be found in medical textbooks, encyclopedias and related medical journals.  This text will serve as the first collection of articles on customized repositioning forms written by medical professionals from around the world. The articles have been grouped by anatomical sites. This will help the user to easily flip to the section of greatest interest first. At the beginning of each section, the user will find detailed information on all of the forms offered for that anatomical treatment site, along with diagrams and copy showing the correct use of the form, to be followed by a tips section that gives the user little tips that have been picked up in the field as to the best use of the form.

 

 

 

 

 

 

 

 

 

 

CHAPTER ONE

 

 

FUNDAMENTALS OF REPOSITIONING AND IMMOBILIZATION

 

 

    Once the desired treatment set-up position has been determined for the patient, consideration must be given regarding the day to day reproducibility of that position and the immobilization of the patient once placed into the position. This field guide explores the benefits and utility of customized repositioning devices utilizing a polyurethane foam poured into a polystyrene shell, ALPHA CRADLE^® brand Patient Repositioning Devices. These anatomical forms offer the medical professional an advanced technology that will immobilize the patient in the desired treatment position and will help duplicate that set-up position accurately and comfortably on a daily basis throughout the patient’s treatment plan. Several considerations must be given in order to maintain the proper and effective positioning of the patient receiving external beam radiation therapy. 

    The most important consideration for proper patient positioning is the safety and comfort of the patient. Patients that are secured in an ALPHA CRADLE^® brand repositioning device are not only safely secured inside of their body mold, but the mold serves to increase the level of comfort for the patient as well. The patient’s form serves as a support literally “cradling” the patient in the desired set-up position.  By increasing the level of comfort for the patient, the patient is less likely to move during the treatment. It is much easier to hold a comfortable position over an uncomfortable position. Many times, the body or anatomy being positioned may slowly relax to a more comfortable position that is easier to hold in a relaxed state.  Oftentimes, the patient may not fully understand that the slightest movement may result in a portion of the target being moved out of the treatment beam, inadvertently placing normal tissue into the beam’s path. The forms offer a foam pillow of support that conforms to the patient’s anatomy, offering support to the anatomy in the desired set-up position. As the foam rises, it can be easily maneuvered to create a soft, yet firm support. The forms are deep, averaging 10-12 cm in depth. The forms also offer support to anatomical sites that do not necessarily lay flat on the treatment couch.

    Many breast patients are unable to place their arms fully flat against the treatment couch, usually requiring them to hold their arm in an uncomfortable position. Even when an arm board is offered, it still places the burden of holding the arm completely still on the patient. By using the ALPHA CRADLE^® brand Patient Repositioning System, the patient no longer is forced to hold their own arm in an uncomfortable position. The form can be made to support the arm up and off the treatment couch. By placing the arm deep into the rising foam, a support trough can be made for the forearm and upper arm. This comfortable guide allows the medical professional to place the arm into the mold, allowing the form to hold the patient’s arm in the desired position. This relieves the burden of holding the position from the patient and places the burden where it belongs, on the patient’s form. The medical professional will find that the patient who is comfortable, not being strained to hold a position, will not move during the treatment, or relax their position, resulting in a shift of the targeted volume.

    Many times the customized forms will offer support to the muscles that may be arced off the treatment couch. By using the custom head and neck supports, the medical professional can support the cervical area that may be arced off the treatment couch.  If not supported, these muscles may relax during the treatment, shifting the position during the treatment of the patient’s head and neck. By using the head and neck support, the patient’s neck is comfortably supported in the desired treatment position.  The patient will be positioned in the same position each and every time they return for treatment.

    The foam that is used to create the form has been modified several times over the past decade.  The current foam that has been developed took 7 years to complete. The result is a softer foam that feels smoother to the patient, while offering the same rigidity needed to maintain structural integrity with the forms.  The foam is softer and allows the medical professional maximum flexibility in maneuvering the foam to the desired shape and position.  The foam produced by Smithers Medical Products, Inc. does not contain any amounts of TDI (toluene diisocyanate). This toxic substance is found in most other foams and is controlled in its use by the federal government. Toluene has been controlled by the Superfund Cleanup Act, and is one of the hazardous chemicals controlled by the Environmental Protective Agency hazardous chemical group. Not only is our foam comfortable for the patient, it is also safe for the medical professional who may find themselves making several customized forms each day. The foam has also been developed without the use of harmful CFCs.  This new process to blow foam without the use of CFCs was developed in-house, providing you with the safest and most effective foam available. At Smithers, we are concerned with the safety of the patient, as well as the safety of the medical professional and the environment.

    One area of comfort that is often overlooked is the comfort the customized repositioning forms provide to the medical professional. When you are using a customized repositioning device correctly, you are using a tool that will absolutely hold your patient still, motionless, in the correct set-up position each and every time that you turn on the treatment beam. The customized forms offer you the comfort and security that you are providing your patients with the best treatment and the best chance for successful treatment available today. The patient is able to lay comfortably in the set-up position and hold that position.  You are able to treat that patient knowing that the form will return the patient to the correct position each time the form is used. The form is holding the patient still from the time you turn around and walk out of the room to the time that the patient is removed from their mold. This is peace of mind for you, and for your patient.

    Another important consideration for proper patient positioning is the difference between positioning and repositioning. Positioning aids are an excellent tool for diagnostic radiology. Examples of common positioning aids would include tape, cloth straps, leather straps, plastic head and neck holders, foam sponges and pillows. Positioning aids offer the medical professional varying means to place the patient in a desired position. The problem with positioning aids is that in and of themselves, they do not guarantee that the patient can be placed or fixed back into that position with the degree of accuracy needed for today’s sophisticated radiation therapy 3-D treatment planning. There is no way to guarantee that the device is on the treatment couch in exactly the same position, or that the positioning aid is in the same relationship it was to the patient. Nor is there any way to guarantee that the patient is secured into the device.  For instance, how many different ways can you grab onto an arm holder?  Your arm can be higher or lower than previously set-up. Your hand can grip the arm holder differently each time.  You can relax you grip, shifting position slightly.  When using a standard head and neck positioning

Sponge, the patient is able to move their heads any way they want, back and forth, side to side, strained or relaxed. There is nothing to help the patient put their head onto the device the same way each time they place their head on the sponge. This shows the weakness when using positioning aids: you can never guarantee that the patient is in the same position each time the aid is used, and many times the patient is not truly immobilized.

    Repositioning devices offer maximum reproducibility. The ALPHA CRADLE^® BRAND patient Repositioning System offers the medical professional the best means available to reproduce whatever type of set-up is needed. Forms have been developed for patient’s arms, legs, chest, breast, head and neck, head, one leg on the table with the other leg off, a patient in the sitting position, patients laying on their side, prone, supine, kyphotic patients, and even whole body forms with the patient being treated in a sitting position. Forms can be customized to fit infants, children, young adults, thin adults, obese patients and every size and shape between. Forms can be customized for any anatomical site on any size or shape patient that will work in conjunction with the equipment used by any particular medical facility. Many times, forms are developed to work with a particular type of treatment couch or piece of necessary medical equipment. The customized devices will complement many of the standard pieces of equipment that can be found in the average treatment room.

    The reproducibility of the patient from simulation to their last treatment must be maintained on a daily basis. A new study shows that while the relationship between skin marks on the surface of the skin and the underlying anatomy can change, marks on the surface of the cradle may offer the optimum means to reposition the patient. By indexing the customized forms, to the treatment couch, the medical professional can first verify that the forms are in the same relative position to the isocenter for each and every treatment. Once the patient is in their form, the patient will wiggle into the most comfortable position, being the exact position in which the form was made. If the patient is not in the same position, they will not be comfortable and will move until they return to that comfortable position. By maintaining reproducibility, the whole purpose of treatment planning, to deliver a lethal dose of radiation to the tumor without delivering a lethal dose to healthy tissue, can be achieved. Reproducibility offers the best means to successful radiation therapy treatment planning. Often times it is overlooked that the best treatment plans, the best equipment, the best staff available is completely useless unless the radiation dose is delivered to the same point each and every time. The better the reproducibility, the more likely the medical professional is to deliver lethal radiation to the tumor site while delivering minimum collateral damage to healthy tissue.

    Another important factor in proper patient positioning is time.  Time is a precious commodity that is irreplaceable. Most patients and families of patients would find it intolerable that there are decisions being made regarding the treatment of their loved ones, based not on merely what is the best course of action for successful treatment, but what is most cost effective and what offers the best time savings. If a device takes too much time to use, oftentimes it is removed from consideration, regardless of the potential for increasing treatment effectiveness.  It is in this area that lies one of the greatest misconceptions of customized repositioning devices. A technologist once reviewed the forms and stated that although they believed the forms would help increase patient comfort and reproducibility, they didn’t have the time to make one on each of their patients. To which I stated that if time was that precious to them, they couldn’t afford not to make the customized repositioning forms.

    Using repositioning devices will actually reduce the amount of time spent with each patient over the course of treatment. In a difficult breast set-up, the time needed to make an ALPHA CRADLE^® form, 10-15 minutes, can be made up often in the first treatment.  Consistent use of the forms will reduce the amount of time needed to correctly set-up the patient in the correct set-up position.  By indexing the forms to the treatment couch, the medical professional can quickly place the form in its original position. The patient is carefully lowered into the form where they will wiggle into their comfortable yet snug original position.  Many times the need for port films can be reduced or even eliminated. By using customized forms on each patient, you can reduce the amount of time being spent on each machine just getting the patients in the correct set-up position.  Thus the forms can actually increase the amount of patients that can be safely and effectively treated.

    A final consideration in proper patient positioning is the correct use of the customized repositioning form. Many negative attitudes regarding customized repositioning forms have been made on the sole basis of an individual’s improper use of the material. Oftentimes the correct procedures are ignored resulting in a poorly made device that will actually reduce the effectiveness of treatment, not increase it. Effective forms can only be made when the medical professional has reviewed the correct and proper procedure for making a form, following the instructions carefully. Oftentimes, substitutes are made in materials that yield entirely different results than when using the materials provided.

    It was only after I had personally visited over 500 facilities across the United States, that I realized the need for a detailed video showing what a properly made customized repositioning form should look like. Many times upon an on-site visit, it comes out that the video has never been watched or the safety sheets reviewed. In almost every circumstance where foam has been spilled while making a form, the correct procedure was not followed or the safety equipment and procedures were ignored.

    Proper formation of a customized repositioning form should allow the patient to fit deeply inside the form and the form should fit snugly.  This is worth repeating. Proper formation of a customized repositioning form should allow the patient to fit deeply inside the form and the form should fit snugly. If the patient doesn’t sink deep into the form, you will not receive the maximum effectiveness of the device. A loose fitting form or a form that looks more like a surf board than a body mold will always be disappointing in its effective repositioning use.

    To maximize the effectiveness of the form, the instructions must be followed carefully and correctly. The quality of a correctly made form is astounding. The form will be at least 10-12 cm up off the treatment couch. When viewing the patient from above, they will appear to be deep inside the form. This assures the medical professional that the patient’s fit is secure in the mold. The patient will not be able to move around once placed inside. As the form guides the patient’s arm, the form should actually curve up and around part of the patient’s arm, making a deep groove. The sides of the form should rise to the top of the patient’s side, making a snug guide to keep them in place for each treatment. If you see a form that does not rise up against the patient, with deep grooves for the arms and tight sides that position the patient, you are not using a form that is effective. This is why it is so important that as the foam rises, the medical professional use their hands to guide the foam tight against the patient. The form will only fit as snugly as it has been made.

    Many times we are asked which system is better, the ALPHA CRADLE^® Patient Repositioning System, or the ALPHA CRADLE^® Mold Maker II. Each system offers its own advantage over the other. Each system offers a different means to achieve the same goal of maximum effectiveness in the proper repositioning and immobilization of the patient. The ACPRS was first introduced to the United States in 1981, as the first polyurethane based customized immobilization system utilizing polysyrene shells. In 1984 the ACMMII was developed so that a customized immobilization form could be made for a CNS patient’s body and face, safely and effectively, without the use of polystyrene shells. The end result with the ACMMII was that it could be used to make customized forms on any and all anatomical sites.

   

ALPHA CRADLE® PATIENT REPOSITIONING SYSTEM

    This is the official and proper name to what is referred to as “ALPHA CRADLES” in the medical field. ALPHA CRADLE^® is a registered trademark of Smithers Medical Products, Inc. (see Chap. 2). A “kit” includes everything needed to successfully make the particular form. For example, one of our most popular forms is the BF4-E. It is a breast form with an 18-inch width, allowing it to be used in most CT scanners. This form has a 54-inch length. When this form is ordered, the polystyrene shell, sheeting material, and foaming agents are all included as part of the kit. The foaming agents are usually packaged separately for conveniences regarding shipping. Associated literature, instruction sheets and Material Safety Data Sheets are also sent with each order. For first time orders, a safety kit including a safety and education manual, a step-by-step detailed video, tyvex smock, latex gloves, OSHA approved safety goggles and a mandatory safety test is included.

    Some of the benefits associated with this system would include convenience, simplicity and standardization. Over 40 different anatomical shells are currently offered, offering you the convenience of using the exact shell you need for each different treatment site. The forms are standardized for each anatomical site. If you are used to using a form that measures 24”x 24”, each time you order the form it will be the exact same length, width and height. This allows you to plan exact measurements when using the forms. The ACPRS offers simplicity in design and fabrication. It requires a minimum amount of manual dexterity and experience with the system. It has been designed so that someone who has never used the system can make a quality form the first time simply by referring to the instruction sheet. Most forms are now placed inside a protective bag, the foam added to the inside of the shell with the open end of the bag carefully tucked underneath, and patient placed into the form. This offers the medical professional true simplicity in the design and use of the system.

 

ALPHA CRADLE^® MOLD MAKER II

    The ALPHA CRADLE^® Mold Maker II is the name of our patented system that allows customized repositioning and immobilization forms to be made without the use of the polystyrene shell. The device includes a base board measuring 24”x 34” including slots cut horizontally and vertically, and an easy carry handle. A brass medallion has been placed in the center of the board. The device also includes an assortment of dividers that are used in conjunction with the slots to hold the bag of expanding foam tightly against the patient as the form is being fabricated.

    The ACMMII is an easy-to-use, hands on device. Basically, the user is pouring foaming agents into a bag, placing the bag of foam onto the base board, laying the patient on top of the bag in the desired position, and then using the dividers to hold the bag tightly against the patient. The bag can be lifted up and off the board to accommodate different molding needs. The bag can also be taped around the extremities in a crescent shape to increase the deep groove that guides the extremity.

    Some of the benefits of using the ACMMII over the ACPRS would include cost and space savings, and true customization and convenience. Most adult molds can be made for less than half of the cost of using the ACPRS. This is due to the fact that you are only using a bag and the foam to make the form, not the polystyrene shell. Since you only need the foaming agents and not the shells, you can store ten kits of foaming agents in the space that is normally required for one or two ACPRS shells. This can be an important consideration for a small hospital or freestanding facility that may not have the convenience of ample storage space. Perhaps the best convenience that is offered by the ACMMII is the ability to create whatever type of mold is needed on any treatment site without the need to store large amounts of different shells. One set of foam is all that is needed to make a head and shoulder form, or a thorax, breast, lower extremity and pelvic form. The medical professional can also create a truly customized anatomical form. It does not have to be a certain width or length, as the shells necessitate. Each form can be tailored to the individual need of each specific patient.

    A detailed description on the correct use and set-up for each form can be found at the front of each section of this field guide. These detailed descriptions will be tailored to the specific site covered by that chapter. Two different helpful hint sections will be listed. One will detail the proper procedures to be followed when using the ALPHA CRADLE^® Patient Repositioning System and the other when using the ALPHA CRADLE^® Mold Maker II. These helpful hints are actual means and tips from the medical professionals that have been using the devices in the field on patients over the past decade. Many of the tips were developed by SMP and offered as suggested tips to increase the utility and benefit of the device. These tips are offered to promote discussion and not intended to replace the instructions given with each form. These tips will often add to the effectiveness of the device depending on the procedures and needs of your department or facility.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Patient Positioning and Immobilization In Radiation Oncology

Some Considerations:

By Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

PATIENT POSITIONING AND IMMOBILIZATION IN RADIATION ONCOLOGY:

SOME CONSIDERATIONS

BY Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Durham

 

INTRODUCTION

    Uncertainties associated with the delivery of a prescribed radiation treatment can be divided into two groups; uncertainties of dose (i.e., in homogeneities, dose calculations, variables in machine output and uncertainties in patient-beam geometry). Geometric uncertainties can be broadly divided into these inherent to mechanical inaccuracies in the treatment machine and those related to patient positioning which will be the focus of this report.

    Geometric discrepancies caused by mechanical limitations/problems in the machine (beam angle indicators, beam-light coincidence, isocenter accuracy, etc.), in theory, can be eliminated by very rigorous testing and adjusting. In every day practice, however, we accept the fact that not all discrepancies can be corrected. It has been suggested, that displacements caused by mechanical machine inaccuracies, even when they are within the specified minimum requirements, can be <5mm while uncertainties of set-up and position of target volume due to patient or organ motion can cause errors of up to 8mm resulting in a combined uncertainty of <10mm.³⁰  Variations in the day-to-day set-up are difficult to contend with because patients tend to move and there are inaccuracies aligning the treatment beam to the set-up marks. The American Association of Physicists in Medicine (AAPM) recommend <5mm spatial uncertainty.¹  Several studies show that present practice does not meet these recommendations. Rabinowitz et al. showed in a study of 71 patients, that in 20% of set-ups, the spatial error was more than 10mm.²² Rosenthal et al. found a total uncertainty (random and systematic) of 0.7 cm in a retrospective review of 318 port films in 51 patients treated for head and neck malignancies using a bite block immobilization system.²⁴ Byhardt et al. found, in a study of port films of 337 patients, that set-up errors >5mm occurred in 15% of the set-ups and in 10% of the set-ups, the error was >10mm.⁷

    Although impossible to eliminate, spatial uncertainties caused by patient motion can be reduced by using an aggressive immobilization system and highly trained, compulsive technologists who take the time to carefully set up the treatment and pay meticulous attention to details. In this report, we will review the clinical implications of spatial inaccuracies and techniques to address the problem discussed.

 

I. GENERAL BACKGROUND

 

A. TARGET MARGINS AND FIELD DESIGN

 

    In general, most treatment fields are designed to treat volume plus “a margin.” This margin is added to account for three factors. First, dose fall-off at the beam edge. Second, inaccuracies in defining the target volume, and third, inaccuracies in patient-beam set-up. The first factor is illustrated in Fig. 1. The edge of the beam-defining field light usually coincide with the 50% isodose level (Fig.1).

 

(diagram)

 

Fig. 1 The geometric edge of a treatment field is usually defined by the 50% isodose line, however, the dose is often prescribed to the 95% isodose line. The distance between the 50% and 95% isodose lines is, in most linear accelerators, approximately 5mm.

 

The distance from this geometric field margin to the 95% line varies from machine to machine but is often ~5mm on a linear accelerator. A 5mm margin for inaccuracies in target identification is a minimum value given the difficulties interpreting conventional diagnostic images and transferring this information to the simulator films. The third area of uncertainty lies in the reproductivity of the geometric patient – beam alignment and the probability of organ and patient motion. Many radiation oncologists add a modest 5mm margin to compensate for these uncertainties (Fig. 2). A combined margin of > 15mm is commonly added around the target volume. Under optimal circumstances, including the use of rigid patient immobilization, 3-D treatment planning systems, and conformal beam shaping, this margin may be sufficient. In the absence of these technologies, however, larger margins may be necessary.

 

(diagram)

 

Fig. 2 Margins are added around the target to compensate for uncertainties of defining the target volume, uncertainties in the set up accuracy and patient motion, and for penumbra of the beam.

 

 

    When margins are added around the target to compensate for uncertainties, a large volume of normal tissue may be irradiated. A small reduction of the margin can have a significant effect on the volume of normal tissues that are exposed. The volume of normal but exposed tissue (outside the tumor) can be calculated for different target sizes and with different margins. The results of an idealized calculation are shown in Table 1 for a patient treated with a single field for a rectangular target volume irradiated with various size margins. The target is assumed to involve the entire 20 cm thickness of the patient. The target size shown in Table 1 represents the two dimensions perpendicular to the beam. As shown, a significant reduction in the volume of incidentally irradiated normal tissue can be recognized if the margin is reduced. For example, if the margins around a 10 x 10 cm target is reduced from 15 to 10 mm – a 5 mm reduction – in a 20 cm thick patient, the volume of tissue within the irradiated field is reduced from 2645 cm³ to 2420 cm³ - a reduction of 225 cm³. These numbers are only approximate and do not reflect the effect of the beam divergence or the use of multiple beams.

    Since radiation induced complications do not occur in tissues that are not irradiated²⁹, it is beneficial to minimize incidental irradiation of normal tissue. Keus et al.¹⁶ and Letschert et al, have shown that decreasing the volume of normal tissue within the irradiated field reduces the complication rate. Letschert et al.¹⁸ also found that by decreasing the volume of irradiated small bowel by a factor of 2, the total dose can be increased by 17% while the incidence of small bowel complications is unchanged. Reduction of the complication rate afforded by reducing the volume of irradiated normal tissue, may facilitate dose escalation and improved local tumor control rates. Goitein et al.¹³ has predicted, in an idealized mathematical model, that by decreasing the field margins by 5 mm in a supraglottic field, the total dose could be increased to where a 15% improvement in tumor control probability could be achieved without an increase in the normal tissue complication rate.

Table 1

Total volume of irradiated tissue versus tissue versus volume of normal tissue irradiated as a result of margins

(20 cm thick patient)

 

(diagram)

 

Table 1 The total volume of tissue and the volume of normal tissue within the geometric margins the treatment fields. A 10 x 10 x 20 cm target size is assumed. The volume of normal tissue is calculated by subtracting the target volume from the total treatment volume.

 

    The change from colbalt-60 machines to linear accelerators, where the penumbra is much sharper and the dose is more uniform within the geometric edges of the field, has made it possible to reduce the tumor margins. The rapid dose fall-off near the edges, however makes even small beam displacements more critical. The introduction of customized beam-shaping blocks with divergent edges has further reduced the penumbra. It has also made it possible to shape the beam so that it more closely conforms to the shape of the tumor. Prior to custom shielding capabilities, tumor margins were sometimes excessive because blocks were generally limited to standard shapes. Areas that previously could not have been shielded can now be blocked, thus reducing the volume of normal tissue irradiated.

    Advances in 3-D diagnostic imaging, particularly CT and MRI, have improved the accuracy of target volume localization and may facilitate the use of smaller margins. It is important, however, to recognize that these diagnostic modalities may not be ideal. If the extent of tumor involvement is underestimated, marginal misses may occur. The treatment fields can also be designed with more confidence when three-dimensional treatment planning systems such as the Virtual Simulator*²⁶ is used. This system allows the user to view the tumor from any arbitrary direction and to determine the “optimal” beam orientation. The shape of the treatment field can be designed to closely resemble the shape of the target in the beam’s-eye view, thus limiting the volume of normal tissue within the radiation beam. The ability to limit the volume of normal tissue in some instances may allow higher doses to be delivered in the target, thus increasing the probability of local tumor control. ^27,28 However, precision and effective immobilization techniques are essential.

 

B. THE EFFECT OF MISALIGNMENTS

    An important area requiring precision is the geometric alignment of the patient on a day-to-day basis and the accuracy with which each machine parameter is set by the technologists. To miss part of a tumor once or twice during a treatment course could markedly reduce the dose to that segment of the tumor depending on the total number of fractions. Similarly, inadvertent movement of a critical structure into the radiation beam during a few treatments might cause severe morbidity. Failure to deliver the pre-scribed dose may be prevented by the use of effective patient immobilization. The development of tools and techniques with the goal of positioning and

 

* Sherouse Systems, Inc.

(bottom of page)

immobilizing the patient, however, has not kept abreast with the development of modern treatment techniques. The interest in treatment reproducibility has primarily been in the head and neck area and several immobilization devices for this purpose have been described.^{2,11,12,14,15,19,32,33}

    Some older studies of mantle fields suggest that inaccuracies in patient set up may impact on local tumor control. Maruyama et al. reported a 33% recurrence rate in sites adjacent to the blocked areas in patients with Hodgkin’s disease involving the mediastinum.²¹ Rubin et al. a 12% marginal recurrence rate in patients treated for Hodgkin’s disease.²⁵ Marks and Haus presented data from a retrospective review of portal films of 902 set-ups on 99 patients with Hodgkin’s disease and malignant lymphoma and found that in 36% of the set-ups, the position of the shielding blocks were not duplicated as planned.²⁰ In 10 of 99 patients the disease was not controlled locally. Two of these failures were at the margins of the fields and were shown by portal films to be correlated with positioning errors leading to reduced dose at the sites of recurrence. More recently, Kinzie et al. reported in a Patterns of Care Study, on the consequences of field misalignments in 155 patients treated for Hodgkin’s disease.¹⁷ They found that with inadequate tumor margins, the in-field and marginal recurrence rate increased from 7% to 33%. From these studies one might conclude that errors in treatment delivery, including patient positioning errors, may be a significant cause of marginal recurrence. It is probably safe to assume that, in these fairly old studies, patient immobilization and target identification were not as rigorous as they are today and that marginal recurrence rates therefore are likely to be lower today.

    Goitein et al. using a model, studied the effect of under dosage at the perimeter of the treatment field caused by random immobilization errors.¹³ They found that as much as 12% improvement of tumor control probability could be achieved by good immobilization techniques in a supraglottic field. The authors conclude that good immobilization as a means of improving tumor control in supraglottic carcinoma is important. Recognition of these spatial uncertainties is one of the reasons why margins are placed around the tumor volume, as described in the previous section.

    The need for effective patient immobilization to reduce misalignments has been recognized by many radiation therapy centers as evidenced by the increasing number of studies reporting on immobilization techniques and the ability to reproduce the planned treatment.^{6,8,9,10,23,24,31,34}

 

II. PATIENT REPOSITIONING

    In all of radiation therapy, it is necessary to establish the precise position of the target in three dimensions with respect to some visible external marks. A realignment system, used to aid in the repositioning of the patient, is usually mounted in each treatment room. This system consists of three laser lines projected such that each line coincides with one of the three axes and all lines coincide at the isocenter of the particular machine in the room. One line is projected from the ceiling and coincides with the in-out motion of the couch (sagittal plane in the patient). Two opposed crosshairs are projected from the walls of the room; one coincides with the up-down motion of the couch (transverse plane in the patient), and the other with the right-left motion of the couch (cornal plane in the patient). It is important to recognize that the laser alignment system is fixed with respect to the treatment machine and that the patient must be realigned with these lines for each treatment session. The alignment lines, marked on the patient’s skin and/or on an immobilization device during the target localization procedure, are used to realign the patient with an identical alignment system in the treatment room. In most treatments it is desirable to place the isocenter of the therapy machine in the center of the target volume and then, through changes on the collimator, couch, and gantry angles, direct the beam at the target. If the marks and the target do not move with respect to one another, realigning the patient with these lines will insure that the target is repositioned with respect to the radiation beam.

    It is not sufficient to align the patient with just three points. Rather severe errors in the treatment can result if only the isocenter is realigned, particularly when large fields are used (Fig. 3).

Practical the entire body of the patient must be aligned with the alignment lines in order to assure that the treatment field covers the intended volume. This leads to other considerations such as the precise coincidence of the entire alignment line with the axes of the motions of the couch. The sagittal alignment line must, for example, follow precisely the in-out motion of the couch. It also becomes essential to immobilize almost the entire patient even when just the breast or the prostate is treated. Alignment marks can then be made on the immobilization devise as well as on the skin, and, as long as the patient is repositioned correctly in the device, the entire treatment field will be repositioned correctly.

 

A. REALIGNMENT MARKS

    Alignment marks made on the patient’s skin are often unreliable as soft tissue tends to move over underlying deeper organs. If we could for just a moment think of the patient as a mannequin where the surface is rigid we would realize that marks made on the surface will always remain in the same fixed place with respect to deeper points. In a human, on the other hand, the skin can be moved over underlying bone anatomy. For example, a mark made on the back of the hand when the fingers are extended will move with respect to the underlying bones when a fist is made. Skin marks made on breast tissue can easily move several centimeters with respect to the chestwall, the suprasternal notch, or other rigid points on the patient’s chest. Likewise, set-up marks made on the skin in the pelvis of an obese patient will move with respect to underlying bony anatomy. The distance by which these marks travel depends on the thickness of the soft tissue layer between the skin and the rigid bones. Skin marks are most satisfactory when the target is superficial, for example, when a palpable lymph node is treated. In most radiation treatments, however, the beam is directed at a deep-laying tumor. In these situations, skin marks made during the treatment simulation procedure are not reliable. Set-up marks made on the immobilization device is more reliable than skin marks as long as the patient is repositioned correctly in the device. Marking the alignment lines on an immobilization device also eliminates the risks of the marks washing or wearing off and prevent migration because they do not need to be reinforced.

 

III. PATIENT IMMOBILIZATION

    The need for effective patient immobilization has increased as technologies developed during recent years have improved the ability to identify the target and to design the treatment fields to conform to the target. One of the most important aspects of immobilization is to position the patient in a practical position. The patient’s position during treatment must be decided with consideration given to the anticipated beam arrangement. The treatment planning team must know what type of beam arrangement is anticipated prior to making the immobilization device. It is also important to place the patient in a comfortable yet reproducible position. A patient who is uncomfortable will have difficulty in maintaining the position even for short periods of time and without proper supports the position may be difficult to reproduce on a day-to-day basis.

    Another essential consideration when immobilizing a patient is the need to fix at least two points with respect to one another, one on each side of the intended treatment field. For example, when the para-aortic nodes are treated, the chest and the hips need to be fixed to prevent curvature of the spine and the trunk of the body. When a soft tissue sarcoma in the arm is treated, the chest, arm, and hand need to be fixed with respect to one another. A rotation of the hand can change the relative position of the muscles in the arm thus, possibly moving the tumor out of the radiation beam. The ability to immobilize two bony points with respect to one another in a rigid fashion is related to the thickness of the soft tissue which lies between the bony prominence and the immobilization device. If the immobilization device is in direct contact with the skin surface, for example in the hips, the patient’s bony pelvis can still be rotated. In the head and neck area, where bony prominences are generous and the thickness of soft tissue is small, immobilization can be very effective. However, if only the tip of the nose, which consists of cartilage and soft tissue, is a very flexible prominence. Immobilization of portions of the body which contain fewer bony anchor points are most difficult and may therefore require that the immobilization device includes large sections of the body. Immobilization of the pelvis, for example, requires that the immobilization mold extend from the chest to below the feet and that it fits tightly underneath and on each side of the patient. Changes in the position of the feet also changes the appearance of the bony pelvis on a radiograph and could lead to inappropriate field shifts when port films are reviewed. A thin patient would be very uncomfortable in a tight-fitting mold if the bony prominence did not fit precisely into the grooves formed when the mold was made while in an obese patient it might be more difficult to detect a positioning problem.

    The difficult task of immobilizing and repositioning the patient has been made possible through the ALPHA CRADLE^®* brand Patient Repositioning System. ALPHA CRADLES^® consists of a series of Styrofoam^®** forms that roughly match a patient’s anatomy. Two bottles of foaming agents are mixed and the content is poured inside the form. With a large polyvinyl bag covering the form, the patient is placed in the desired treatment position in the form. The foam expands and fills the space between the patient’s skin surface and the Styrofoam^® form, thus, forming a mold under and on the sides of the patient. The height of the sides of the mold can be monitored by the user by extending the bag up to the sides to desired height. It is generally a good practice to make the sides at least 6” high and in very close contact with the patient’s skin to form a tight “cradle” (Fig. 4). This can be accomplished by either pushing the foam while it is soft toward the patient’s sides or by stretching masking tape across the ALPHA CRADLE^® to force the foam toward the patient until the mold is hard.

 

* Registered by Smithers Medical Products, Inc.

** Registered by Dow Chemical

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(diagram)

 

Fig. 4 An effective Alpha Cradle® form must fit tightly to the patient’s skin surface (arrows) and “cradle” the patient.

 

ALPHA CRADLES^® constitute and excellent immobilization system which can be adapted to any part of the patient’s anatomy. In the following paragraphs, the use of ALPHA CRADLE^® in the Department of Radiation Oncology at Duke University Medical Center is briefly described. Detailed descriptions can be found elsewhere.

 

A, HEAD AND NECK IMMOBILIZATION

    Immobilization techniques of patients treated for malignancies in the head and neck region are probably the most advanced and have been tested more than any other system. The need for rigid head and neck immobilization is prompted by the often very narrow margins between tumors and critical organs such as the lens of the eye, the brain stem, optic chiasm, and the cervical spinal cord.  We have elected to use customized supports that fit tightly to the back of the patient’s head, neck, and shoulders. Alpha Cradle^® brand foaming agents* poured into a plastic bag placed under the head and shoulders expands and fill the empty space behind the patient. This support offers a comfortable cup into which the patient’s head rests. When this support is hardened, a thermoplastic sheet, which is soften in hot water, is draped over the patient’s face from the middle of the forehead to below the chin. This thermoplastic sheet is attached to a base plate which in turn is fastened to the treatment couch. The thermoplastic sheet will become firm in approximately 5 minutes. Efforts are made to make a tight fit over the bridge of the nose where there is only a thin layer of soft tissue between the skin and the bone, thus, it is an excellent anchor point.

    This head immobilization mask is very tight and must be made with the patient undressed from the waist up. If attempts are made to replace the mask on the patient while he/she is wearing a shirt other than when the mask was made, the patient will complain because it is too tight. In this system, the mask secures the head to the base plate and the base plate is fastened to the treatment couch preventing any skewing or rotation of the head. A unique benefit of many head and neck immobilization devices is that set-up marks can be made on the device (a mask or cast), which obviates the need for unsightly marks on the patient’s face.

 

*Registered by Smithers Medical Products, Inc.

** Registered by Velcro USA

*** Trademark of Smithers Medical Products, Inc.

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B. BREAST IMMOBILIZATION

    Patients treated for malignancies in the breast are probably the most difficult to reposition and therefore require an aggressive immobilization system. In our practice, these patients are immobilized in an ALPHA CRADLE^® form which extends from above the head to just below the knees. The arm on the involved side is raised and a handle onto which the patients can hold on during the treatment is built into the ALPHA CRADLE^® form along with a support the arm³. The set-up marks are made on the ALPHA CRADLE^® form as far from the isocenter as possible, as well as on the patient’s skin surface. Aligning two points separated by a long distance improves the accuracy of the set-up (Fig. 5). The sagittal alignment line is marked on the ALPHA CRADLE^® form above the patient’s head and between the knees as well as on the chest. The transverse line is marked on each side of the ALPHA CRADLE^® form and on the chest while the cornal or horizontal lines are marked on the patient or the ALPHA CRADLE^® form depending on the height above the table top. Because of the complex angles used in the treatment of breast patients, the alignment lines are marked with the patient in the neutral couch position. If there are discrepancies in alignment during the set-up the marks on the ALPHA CRADLE^® form are considered more reliable than the skin marks.

    Patients with large or flaccid breasts often require repositioning of the breast on the chest. A Bravelle™***, single breast immobilization system, is used for this purpose. The Bravelle™ consists of a polyvinyl tube formed to a ring and placed around the base of the breast. The ring is the fastened to a Velcro^®** band placed around the patient’s chest. The breast is fixed in the desired position by tightening the Velcro^® band.⁵

 

C. IMMOBILIZATION OF PATIENTS WITH HODGKIN’S DISEASE

    Patients treated for Hodgkin’s disease are immobilized in an ALPHA CRADLE^® form which extends form above the head to below the knees. Handles are built into the superior aspect of the device for the patient to hold onto during the treatment.⁴ These handles help in reproducing the arm elevation and also prevent the patient from having to strain to maintain the elevated arm position. Alignment marks are made both on the ALPHA CRADLE^® form and on the patient’s skin surface. The sagittal alignment line is marked on the patient’s chest and abdomen and on the ALPHA CRADLE^® form above the head and between the knees. The transverse line is marked on the chest or abdomen, depending on whether the mantle or the para-aortic fields are treated, and on the ALPHA CRADLE^® form. The coronal or horizontal lines are marked on the patient or on the ALPHA CRADLE^® form depending on the height above the table top.

 

D. THORACIC IMMOBILIZATION

    In our clinic, patients with thoracic malignancies are immobilized only if they are treated with curative intent or are candidates for three-dimensional treatment planning. ALPHA CRADLE^® forms extending from above the head to the knees are then used. Alignment marks are made on both the patient and on the ALPHA CRADLE^® form as described for patients treated for Hodgkin’s disease.

 

E. PELVIC IMMOBILIZATION

    Patients treated for prostate malignancies are immobilized in an ALPHA CRADLE^® extending form the mid-chest to below the feet.⁶ By including the feet in the mold, variation in the foot position which would also change the orientation of the bony pelvis, is prevented. This mold extends approximately 6” above the couch top on each side of the patient. Set-up marks are made on the ALPHA CRADLE^® form as well as on the patient’s skin. The sagittal alignment line is marked on the patient’s skin and on the ALPHA CRADLE^® form between the legs from the thighs to the feet. Two transverse alignment lines are marked on the patient and on the ALPHA CRADLE^® form; one on the pelvis and one just below the knees. The mark below the knees, where there is a very thin layer of soft tissue over the tibia, is to verify that the patient is repositioned correctly in the cephalad direction. The coronal or horizontal lines are marked only on the ALPHA CRADLE^® form. If there is a discrepancy between the marks on the patient’s skin and on the ALPHA CRADLE^® form at any time during the set-up, the technologists use the marks on the ALPHA CRADLE^® form. These marks do not move with respect to deep rigid anatomy and with the patient repositioned correctly in the ALPHA CRADLE^® form the treatment geometry is reproduced.

 

1. “BELLY BOARD”

    In a large number of patients it is desirable to move as much as possible of the small bowel out of the treatment field. The patients are positioned in the prone position hoping that gravity will cause the small bowel to move anteriorly. An ALPHA CRADLE^® form is built which has either an opening under the pelvis to remove and resistance for the bowel, or with a compression roll under the lower pelvis to force the small bowel superiorly. The reproducibility of such set-up can be quite difficult, particularly in patients who find it difficult to assume the prone position. Figure 5 illustrates a patient where the small bowel was outline on a series of CT images using a three-dimensional treatment planning system. The treatment field was angled and designed to avoid the small bowel. Several days later, the planned treatment fields were simulated. The patient was given oral small-bowel contrast and radiographs of the planned fields were taken to verify the exclusion of the small bowel. Figure 5 shows a treatment field template generated from the 3-D treatment planning system superimposed on the simulation radiograph. Considering the motion of the small bowel, the reproducibility of this complex field is excellent. Precise repositioning of this very difficult elderly, handicapped patient would not have been possible without the ALPHA CRADLE^® form.

 

(diagram)

 

Fig. 5 A template of the treatment field produced from the 3-D planning system and superimposed on the simulation radiograph. Small bowel contrast and bony landmarks confirm the excellent patient repositioning in a prone “belly Board” Alpha Cradle^®.

 

F. IMMOBILIZATION OF EXTREMITIES

    In our clinic, ALPHA CRADLE^® forms are used for patients treated for lesions in an extremity. In these patients it is critical for the treatment planning team to know the anticipated beam arrangement prior to designing the first immobilization device. The position of these patients is often complicated by efforts to avoid irradiating unnecessary volumes of normal tissue. When one lower extremity is treated, for example, it is crucial to move the opposite lower extremity out of the path of the beam (Fig. 6). ALPHA CRADLE^®

Forms are built to immobilize the patient from the waist to below the feet. When one upper extremity is treated, the entire chest and arm is immobilized in an ALPHA CRADLE^® form (Fig. 7).

 

(diagram)

 

Fig. 6 Lower extremities immobilized and fixed with respect to the pelvis in a patient with a tumor in the right leg. The legs are separated to keep the unaffected leg away from the path of the beam in anticipation of oblique fields.

 

(diagram)

 

Fig. 7 Upper extremity immobilized and fixed with respect to the thorax in a patient with a tumor in the medial aspect of the lower arm. Repositioning of the fingers into grooves made in the mold prevents rotation of the hand. Alignment marks are made on the ALPHA CRADLE^® form above the head (not shown) and between the thighs.

 

G. CRANIO-SPINAL IMMOBILIZATION

    For both adult and pediatric patients treated to the entire Central Nervous System (CNS), a prone head Styrofoam^® form is used in conjunction with a body form. Foaming agents are used around the face and the body. After the ALPHA CRADLE^® form has hardened, the patient is asked to raise the head and a thermoplastic sheet is stretched across the facial portion of the head support. When the patient’s head is repositioned, the soften thermoplastic sheet is gently presses against the patient’s face, particularly over the bridge of the nose to provide a tight fit. Openings are eventually made on each side of both the thermoplastic mask and the ALPHA CRADLE^® form to allow the eyes to be visualized during the set-up.

    The CNS ALPHA CRADLE^® form has replaced our total body plaster casts which were heavy to handle and usually required two days to dry. The ALPHA CRADLE^® form is made in less than 30 minutes and the simulation procedure can begin immediately. This is a very important aspect because these patients often need to start the treatment with short notice. We also find that it is easier for the patients to enter and exit the ALPHA CRADLE^® form than the plaster cast. The patient for whom we made this ALPHA CRADLE^® form was a paralyzed youth who it was felt, would not have been able to get into the plaster cast without a lot of help. The set-up reproducibility, confirmed by weekly port films, was excellent.

 

H. MISCELLANEOUS

    ALPHA CRADLE^® BRAND patient Repositioning Systems are used in our department for many other situations. For example, patients that are treated in decubitus position, patients that appear to be difficult to reposition, obese patients, and pediatric patients. One ALPHA CRADLE^® form was recently made for an elderly deaf and mute patient who was worried about falling off the narrow treatment couch. We also use ALPHA CRADLE^® forms for positioning patients receiving hyperthermia treatment and for companion animals (cats and dogs) treated in our department for spontaneously occurring tumors.

 

IV. RESULTS

    We feel that it is crucial to routinely review port films to evaluate performance and to screen for any systematic errors. During the efforts to improve our immobilization techniques, a retrospective review of port films was made to determine the frequency and magnitude of patient-beam misalignment. The results of the port film review of patients treated with newer immobilization devices were compared with the findings in a similar group of patients treated using an earlier version of the immobilization device. Patients treated for prostate carcinoma had previously not been immobilized, therefore, the results from the port film review of the immobilized patients were compared with a similar group of patients without any immobilization device. In all of the disease sites for which ALPHA CRADLE^® Patient Repositioning Systems are used, we have improved the patient-beam alignment rates as shown in Table 2. Despite these improvements in patient-beam alignment, we will continue to perform routine retrospective port film reviews and to seek superior methods of patient immobilization.

 

Table 2

Frequency of treatment field misalignments determined on retrospective port film review for various treatment sites

 

(diagram)

 

*   Port film review included only routine port films

** Current immobilization is compared with no immobilization

+  Current immobilization is compared with that of using a short Alpha Cradle^® form

~  Current immobilization is compared with that of using standard head supports and strips of casting material

 

V. SUMMARY

    In recent years, a number of technologies, which are invaluable in defining the target volume and in determining the optimal treatment plan, have been introduced. The patient’s anatomy can now be observed in great detail from any direction on a computer monitor by “peeling away” the skin and other tissues and organs. A treatment plan can be designed in such a way that the resulting dose distribution conforms closely to the target volume. The increased confidence with which the treatment now can be delivered, along with sharply defined penumbra of linear accelerator beams and the capability to customize the field shape to the target, has lead to the use of smaller tumor margins, thus the volume of normal tissues within the irradiated field is reduced. The reduction of the normal tissue volume within the irradiated field may reduce morbidity and facilitate the delivery of higher doses and hopefully improve cure rates. This approach requires accurate and reproducible patient immobilization.

    The precision with which the treatment now can be planned and delivered has reached new heights, however, the accurate delivery of the treatment depends on the meticulous attention to details by everyone involved. The role of the technologists, who actually deliver the treatment, can never be sufficiently emphasized. However, without effective patient immobilization, the ability to carry out the treatment as planned is compromised.

    Retrospective review of portal films of patients with various curable diseases should be carried out by every radiation therapy department on a routine basis to determine the frequency and magnitude of treatment field misalignments. The results of such reviews will demonstrate any need for improvement and it could also reveal systematic errors in the treatment delivery. The day-to-day set-up variability can be improved with the use of an aggressive immobilization system. This is not to say that an aggressive immobilization system will eliminate all day-to-day set-up variations, but it will certainly reduce the errors in patient-beam misalignments.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER TWO

 

 

MEDICAL DEVICE REGULATIONS AND TRADEMARK USE

(Cover page)

 

    If I could add one requirement to the successful completion of any type of medical degree, I would require that each individual take a course detailing the law regarding medical device regulations and trademark use. Additionally, I would like to see the Food and Drug Administration begin a comprehensive study in the materials used on humans in the radiation therapy/oncology departments and freestanding centers across the United States. Many centers either are not aware or choose to completely disregard the law regarding the use of medical devices on humans, and the correct use of trademarks and logos in the literature.

    Believe it or not, there are guidelines that detail what is legal and more importantly what is illegal to use on humans for treatment by the medical community. I have often wondered what a hospital administrator would say to a family member of a cancer treatment patient if that family member asked why mom or dad’s treatment device was made of hazardous illegal components that came out of a hardware store. This would be unthinkable I the operating room, yet seems to be standard operating procedure at many facilities around the country. Unfortunately it will probably take a multi-million dollar lawsuit to grab the attention of medical professionals before they take the medical guidelines set forth by the FDA seriously. How would a hospital ever recover if they were the subject of an investigation report by one of the media TV reporters, reporting how a medical facility uses a product that is illegal to use indoors not to mention on a seriously ill cancer patient who is expecting the best available medical treatment available?

    Any company that engages in the manufacture, preparation, propagation, compounding, assembly of processing of a device intended for use by humans, is subject to the regulations set forth and enforced by the Food and Drug Administration. This covers any device intended for use in the diagnosis of disease or other conditions, or in the cure, treatment, or prevention of disease in man or other animals. These devices are controlled on different levels based on their classification. Smithers Medical Products, Incorporated is registered with the Food and Drug Administration and has registered its products with the Food and Drug Administration. This information is not the opinion of the author, but can be found in the federal register, Department of Health, Education and Welfare, Food and Drug Administration, Medical Devices, listing.

    Smithers has had an on-site inspection by the FDA where the company was praised for its manufacturing set-up and operation and for maintaining quality standards in the safe and effective production of safe, reliable, quality medical foam. At Smithers Medical Products, Incorporated, our quality assurance program details our rigid manufacturing, storing, packaging and processing standards. Detailed maintenance and calibration is performed with each batch of foaming agents poured. Our standards at SMP actually surpass the requirements laid down by the FDA. We believe in providing you, the medical expert, with the safest and most reliable product available on the market today.

    It is inexcusable that some medical facilities do not follow the guidelines when considering the products they use on their patients. Many facilities have sought to make their own repositioning forms by using a dangerous, toxic and illegal foam that is sold at hardware stores intended only for outside use. This dangerous practice is not only harmful to the patient, but is in fact more harmful to the medical professionals who use the dangerous chemicals on a regular basis. These dangerous chemicals contain high levels of TDI, toluene diisocyanate. This toxic gas is a carcinogen itself. Oftentimes, some of the staff who may be told to use the product assumes that the product is safe to use, when in fact it is not. If you are not sure whether a product is safe to use, contact the safety officer at your facility, or contact the FDA directly to see if the product or its manufacturer is registered with the FDA. Ask the manufacturer if they are registered with the FDA and also ask if they have had an on-site inspection. This information will assure you that you are using a safe and effective product.

    Be sure to insist that your facility use ALPHA CRADLE^® brand foaming agents. “ALPHA CRADLE^®” is a registered trademark of Smithers Medical Products, Incorporated. As such, SMP is the only company that provides or manufactures ALPHA CRADLE^® brand customized repositioning forms. If you are approached by a representative from another company that says it sells ALPHA CRADLE^® brand customized repositioning forms, buyer beware!

How sure can you be that a company that would misrepresent their product would sell you a safe and effective product. Once again, contact the FDA if you are in doubt. If you see another company offering to sell you an “ALPHA CRADLE^®” please contact our office with this information. We will take the appropriate legal action to stop this type of malpractice.

    I have found that trademark misuse is widespread throughout the medical community. Many times when an ALPHA CRADLE^® brand repositioning form is referenced in the literature, it has not been properly notated. ALPHA CRADLE^® is a registered trademark of Smithers Medical Products, Incorporated. Therefore any time it is mentioned, it requires the use of a “®”, showing that it is a registered trademark. The copy should also reference the owner of the trademark (company) and their address (city, state). Regarding “ALPHA CRADLE^®”, the trademark is a trademark of Smithers Medical Products, Incorporated, North Canton, Ohio.

    By using the term “ALPHA CRADLE^®” when you are using an inferior homemade of generic version, one is deliberately misleading the audience in the type of study that was done and misleading the audience as to the effectiveness of the products. ALPHA CRADLE^®, properly used in reference, makes reference to the brand of customized patient repositioning systems that are developed, manufactured, and marketed by Smithers Medical Products, Inc. We have traced studies from the Chicago area that claimed to have “ALPHA CRADLES^®” in a clinical trial, only to find that they have never purchased “ALPHA CRADLES^®”, and once contacted, admitted that ALPHA CRADLE^® brand patient repositioning systems were not used in the study. This can be misleading to those reading the literature as well as unlawful. Be sure that when you mention a device in your medical report or study, that if in fact it is a device that your facility purchased, it has a legally protected name, mark or logo that you as the author are responsible for correctly notating. Companies have spent literally hundreds of millions of dollars to protect their name of a product. The medical professional that is reporting a finding has the obligation to be accurate in representing what was used in the study and whom it belongs to.

    Information on correct use of trademarks, patents, and logos can be obtained from the patent office, a nearby patent attorney, or by contacting a representative of the company whose product you are using. Oftentimes companies are unaware of the study involving their product and would appreciate a copy of the article. In some instances, the company may offer to provide the samples needed to complete the study.

    By properly reporting what has actually been used in a study, not only is the medical professional complying with federal law, but they are also describing the actual materials used should colleagues want to try to duplicate the study being described. Correctly using brand names of products used allows the reader to correctly understand what the author used, and the results of the use of that product. Most importantly, the medical professional should not become so unprofessional and sloppy as to mention the brand name of a product when they are only referring to a general type of device, not the brand name itself. Negative stereotypes are very difficult to overcome. The authors who have slandered companies and their brand name products should assume the responsibility of correctly and accurately using brand names, trademarks and logos.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER THREE

 

 

REPOSITIONING AND IMMOBILIZING THE BREAST

(Cover page)

 

    One of the most difficult repositioning challenges offered to the medical professional is the successful repositioning and immobilization of the breast. A large flaccid breast offers the greatest challenge for successful replication of the desired set-up position. Smithers Medical Products, Inc. has developed a new tool that can be used to hold the breast in the desired position during treatment. This new device, the Bravelle™ is a device consisting of a reinforced ring that is secured to the patient’s breast through the utilization of Velcro straps. Large pendulous breasts can be supported within the ring with an elliptical piece of polystyrene fabricated by the user. The Bravelle™ keeps the breast from falling laterally during treatment and more importantly helps reduce the amount of lung that may be treated by keeping the breast up on the chest wall. This device makes it possible to treat breast cancer patients that otherwise would not be candidates for radiation therapy due to the enormous technical difficulties they present.

 

ALPHA CRADLE^® BRAND PATIENT REPOSITIONING SYSTEMS:

BF1, BF2R, BF2L, BF3R, BF3L, BF4R, BF4L, BF4R-E, BF4L-E, HS2M, HS2M-E, HS2-E

    No less than 12 different ALPHA CRADLE^® brand Patient Repositioning Devices have been developed over the past 10 years for the successful treatment of carcinoma of the breast. Each of these forms offers its own unique characteristic to customized forms.

Smithers Medical Products, Inc. has also developed a breast tilt board (JVK Omni-Lock^® System Three), and an arms up patient positioner (Adjustable Tee-Grip^®), both currently being used in the field. Together, when used with the Bravelle™, our customized repositioning devices offer the medical professional the most current state-of-the-art technology to successfully immobilize and reposition the patient on a daily basis.

    The current trend in the industry for successful immobilization and repositioning of the breast involves the utilization of the Bravelle™ with the newly extended breast forms. The Bravelle™ allows the treated breast to be set up daily in the same position, while the extended form controls rotation and eliminates unnecessary movement of the anatomy.

    To maximize the efficiency of the extended forms, great care must be given in maintaining a tight fitting form during the fabrication process. It is recommended that 2-3 people work together to maintain the integrity of the form during the foaming process. By placing your hands firmly against the foam as it begins to harden, you will create a tight fitting form that will not allow deviations or movements of the patient’s anatomy. It is also critical that the patient remains completely motionless throughout the fabrication process. Talking, by the patient, should be eliminated or greatly restricted. When the foam begins to rise, it will lift the patient’s head and extremities. As the foam begins to turn to a spongy consistency, carefully push the head and extremities back, deep into the form. Next, push the foam tightly against the patient’s skin. This will create a deep, tight form that will truly hold your patient still throughout the treatment course.

    Ports should be cut carefully after the completion of the fabrication process. Ports can easily be cut with a serrated knife, or with one of the blades provided in the SMP saw kit. Ports should only be cut as necessary, and only as wide as absolutely needed. After the port has been cut, a damp washcloth should be used to wipe out any foam residue that may have fallen into the cradle. Next, the cut area should be covered completely with a cloth or paper tape. This will guarantee that the patient’s skin doesn’t come in contact with the foam material, which can act as an irritant if contacted with skin.

    It is important to index the form according to the position of the form with your positioning lasers. This will allow you to reposition the form on the treatment couch before placing your patient in the form. The patient’s arms should fit deep inside the groove you created in the fabrication process. If a patient has large flabby arms, a small series of tattoos can be placed on the arm where it makes contact with the cradle. This will permit you to duplicate the rotation of the patient’s skin to the relative position of the cradle when they are inside.

 

ACMMII

    The ACMMII offers the maximum customization in the fabrication of breast forms. The best means of immobilization and repositioning is achieved when used with the Bravelle™. Forms can be made from the top of the patient’s hips. Because the ACMMII offers a hands on approach, foam can be diverted from areas where ports may be desired to areas where maximum support is needed. The first helpful hint to making firm, supportive forms is to cut a ½” to 1” thick piece of polystyrene 8” wide and 12” long. This will serve as a base support for the form when placed inside of the bag. The foam will stick to the sides of the base making a strong, almost indestructible form. By placing the base piece inside, this will allow more foam to be used along the sides of the form, extending it to the patient’s hips. This offers the maximum control of patient rotation.

    Unroll the bag of foam that is underneath the patient’s raised arm during the fabrication process. Work the foam into this area and then carefully wrap the bag along the base and sides of the arm. Next, cut pieces of tape and affix them to the bag against the patient’s skin. This will allow the foam to rise up and around 2/3 of the patient’s arm, making a deep and secure groove for the arm.

    If the patient is not able to place their arm flat against the ACMMII board, due to surgery or extreme discomfort, the form can be built up off the board. Place the empty bottle #1 underneath (not inside) the bag of foam. Using the dividers, make a tight fitting guide for the arm support. Use tape as necessary to keep the bag of foam against the patient’s skin. This will allow you to create a customized arm support that reaches up and off the treatment couch, yet securely and comfortably holds the patient’s arm in the desired set-up position.

 

 

 

 

 

 

 

 Breast Positioning Device

For Patients with Large Breasts Undergoing Radiation Therapy

 

 

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

BREAST POSITIONING DEVICE FOR PATIENTS WITH LARGE BREASTS UNDERGOING RADIATION THERAPY

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

 

 

INTRODUCTION

    Several studies have shown that local excision followed by radiation therapy in the management of early stage breast carcinoma yields results that are similar to that of a radical mastectomy.^1,4,6,7

    An increasing number of patients are therefore electing local excision followed by radiation therapy in the management of their disease. A small percentage of these patients present with large/flaccid breasts that, from a technical standpoint, is difficult to treat. In a few patients, these difficulties may be so severe that a mastectomy is recommended. Some radiation oncologists may be reluctant to treat patients with large breasts due to the possibility of poor cosmetic result.⁵

    A large heavy breast tends to migrate cephalad when the patient is in the supine position or it may droop laterally (Fig. 1). When the breast is too far cephalad, the tangential beams across the chestwall may not clear the arm and in patients where the breast is on the lateral chestwall, the lung volume within the tangential fields may be excessive.

 

(diagram)

 

Fig. 1 Large/flaccid breasts tend to droop laterally. Set-up mark, indicated by the arrow, represent just one of many that are made on the Alpha Cradle^® form. Also, note the handle which the patient is holding onto.

 

*Registered by Smithers Medical Products, Inc.

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    Attempts to cause a caudal gravitational shift of the breast by elevating the patient’s shoulders on a slanted board frequently fail because the position is difficult to maintain. In some patients, skin folds may also form between the breast tissue and the skin surface of the upper abdomen and in patients with large pendulous breasts, the tangential fields must be extended farther caudal than is customary, hence including more normal tissue. Treating the patient with a brassiere in place has also been tried, however this precludes set up marks from being made on the patient’s chest. A brassiere also frequently moves the opposite breast closer to the tangential beams and may compromise the needed beam angles. A stockinette around the chest to hold the breast in place tends to compress the breast tissue and thus spreading the volume of breast tissue over a larger area of the chestwall. The tangential fields may then need to be enlarged hence, more normal tissues are irradiated. Skin folds are also more likely to be caused by this compression method.

    Dose inhomogeneity within the breast and chestwall in patients with large breasts presents another area of concern, however, the ability to position the breast in a more advantageous location on the chestwall may address this issue in some patients.

 

POSITIONING DEVICE

    The patients are positioned supine in a half-body ALPHA CRADLE^®* form described in a later report, (see Stabilization Device for Patients Undergoing Radiation Therapy for Carcinoma of the Breast, page 47), with the ipsilateral arm elevated.² The breast positioning device,³ the Bravelle™, which is quite simple to use, consists of a reinforced polyvinyl chloride (PVC) tube with an outer diameter of 7/16”. The length of the tube is cut to loosely fit around the circumference of the base of the breast. A polyethylene barbed fitting is used to close the two ends so that the tube forms a ring. The ring is placed around the base of the breast and a Velcro^® tape, 40-50” long and placed under the patient’s chest, is attached to each side of the ring. The breast is then manually moved into the appropriate position and the Velcro^® tape is tightened so the breast remains in the desired position (Fig. 2A and 2B). The Velcro^® strap is placed “under” the opposite breast within the inframammary fold in an effort to pull the involved breast caudal.

 

(diagram)

 

Fig. 2A The breast ring helps to move and maintain the breast in a more advantageous position during radiation therapy.

 

(diagram)

 

Fig. 2B In some patients, the breast tissue will assume a mushroom-like shape causing a skin fold between the breast and the chest. The computed tomography images illustrate the breast position with and without the breast ring in place. In this very obese patient, with a thick chest wall, the volume of lung tissue within the tangential fields was not changed by the use of the breast ring. However, it was difficult to determine the lateral extent of the breast tissue and by moving the breast anteriorly, it was felt that the margins were adequate.

 

In some patients with large/flaccid breasts, the breast tissue may assume a mushroom-like shape over the ring (Fig. 2A). A 2” high circle or semicircle of Styrofoam^®*, is taped to the breast ring as a retaining wall for the breast tissue (Fig. 3A and 3B). A skin fold will sometimes form between the breast tissue and the chest, particularly in the inframammary fold. To prevent loss of skin sparing in the folds, a piece of Styrofoam^® is placed in the crease between the tissues so they become separated (Fig. 3A).

 

* Registered by Dow Chemical

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(diagram)

Fig. 3A A “retaining wall” taped to the breast device and a Styrofoam wedge used to prevent skin folds…

 

(diagram)

 

Fig. 3B With the “retaining wall” in place, the breast tissue is moved anteriorly.

 

Set-up marks are made on the skin peripheral to the breast itself and on the ALPHA CRADLE^® FORM. The sagittal alignment line is marked caudal to the inframammary fold on the upper abdomen and in the supraclavicular region extending onto the ALPHA CRADLE^® FORM. The transverse alignment line and the medial and lateral fields are marked on the presternal skin, the lateral aspect of the chest, and on the ALPHA CRADLE^® form. Internal mammary and supraclavicular fields are matched in the usual fashion.

 

RESULTS

    The device has been used in 18 patients in our department. In the majority of these patients, the goal has been to move the breast from the lateral chestwall to an anterior position. When the breast was moved more anteriorly, the lateral field margin could, in some patients, also be moved more anterior, thus the volume of lung tissue within the tangential fields was reduced. In some patients, the shift of the breast position was in more than one direction and in one patient the breast was shifted cephalad.

    Another benefit of repositioning the breast from the lateral to medial position is the improved dose uniformity across the breast and chestwall, which occur when the breast is positioned closer to the midpoint between the medial and lateral entrance point of the tangential fields.

    All of the patients treated using the breast ring have developed small areas of moist desquamation in the inframammary fold, which healed soon after completion of therapy. One can surmise that had these patients been treated without raising the breast, the skin reaction might have been more severe. The cosmetic result, recognizing the short follow up (1-29 month), has been excellent.

 

DISCUSSION

    Irradiation of patients with large breasts is technically very difficult and some radiation oncologists hesitate to treat these patients due to the risks of poor cosmetics result. The device described in the report, the Bravelle™, manufactured by Smithers Medical Products, Inc., has made it possible to treat breast cancer patients who otherwise would not be candidates for radiation therapy due to the enormous technical difficulties they present. The reproducibility of the breast position has been satisfactory and no adverse reactions have been observed in 18 patients that have completed radiation therapy using this device.

 

 

 

 

 

 

 

 

Stabilization Device for Patients Undergoing Radiation Therapy For Carcinoma of the Breast

 

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

STABILIZATION DEVICE FOR PATIENTS UNDERGOING RADIATION THERAPY FOR CARCINOMA OF THE BREAST

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

 

INTRODUCTION

    Improved imaging modalities, primarily Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI), and three-dimensional treatment planning capabilities has resulted in increased confidence in the target localization. This increased confidence, along with sharply defined penumbra of linear accelerator beams and the capability to customize the field shape to target, has led to the use of smaller margins around the target, thus the volume of normal tissues within the irradiated field is reduced. The smaller margins also increase the risks for geographic miss, therefore, improved immobilization methods are crucial.

    ALPHA CRADLE^® brand Patient Repositioning Systems have been used for immobilization of patients receiving breast irradiation in our department for approximately 15 years. Ongoing efforts to improve the reproducibility of the set-up of these patients has lead to two major modifications. The addition of a handle to the breast ALPHA CRADLE^® form has been described in an earlier report.¹ This modification improved the repositioning but not to our satisfaction. Recently, another modification has been made which is described in this report.

 

TREATMENT

    The goal of breast irradiation is to treat the chestwall and regional lymph nodes and, in an increasing number of patients, also the breast. Irradiating this very irregularly shaped target while minimizing the dose to adjacent normal tissues requires a complex arrangement of multiple fields angled in different directions across the patient’s chest. Reproducibility of the set-up is difficult since the skin surface in this area often moves with respect to deep-laying tissues. Set-up marks made on the skin surface in this region are therefore unreliable. In obese patients or patients with large breasts, the skin marks can move several centimeters with respect to underlying bony anatomy. The degree of arm elevation on the involved side also plays a role in the position of the skin marks with respect to deeper, fixed tissues. Reproducible patient positioning and the ability to make set-up marks peripheral to the breast itself as well as on a positioning device is crucial to successful radiation therapy of these patients.

    In our breast treatment technique, the breast and/or the chestwall are treated through opposed tangential fields. The internal mammary nodes are sometimes treated in a separate anterior field or, alternatively, are included in the tangential fields. The ipsilateral supraclavicular nodes are treated via an anterior oblique field angled to avoid inclusion of the larynx, the spinal cord, and the esophagus. Since the cephalad margins of the two tangential fields are diverging in opposite directions into the superclavicular area, the couch is angled such that these margins form a common border and the caudal half of the field is blocked to form a vertical match line. The internal mammary field is 5 to 6 cm wide and covers the ipsilateral internal mammary nodes. The deep margin of the tangential fields is blocked to match the internal mammary field. Since the position of either one of these breast fields is depending on the position of its neighbor, misalignment of one field frequently but not always results in misalignment of all fields.

    Traditionally, in all radiation therapy treatments, attempts are made to position the patient “straight” on the couch. However, in order to treat the same volume as the simulation or “prescription” radiograph indicates, it is crucial to reposition the patient exactly as during the simulation procedure. In order to deliver the “prescription treatment”, the patient must be in the “prescription position”, therefore, whether the patient is straight or not is irrelevant.

    The use of a positioning device and an alignment system aids in reproducing the set-up from day-to-day. A small misalignment of the patient with the sagittal alignment line will cause the internal mammary field to be misaligned with the sternum (Fig. 1) and hence, the tangential and supraclavicular fields are also misaligned. A small rotation of the patient’s body with the lateral or horizontal alignment lines causes the deep borders of the tangential fields to be at different depth (Fig. 2). This type of misalignment can occur even when the field edges correctly match the skin marks for the internal mammary and supraclavicular fields. In an effort to reduce this type of misalignments, we use a hemibody immobilization device which the patients feel is comfortable and the technologists like because it is easier to position and treat the patients and the request for field shifts and repeat port films is reduces.

 

(diagram)

 

Fig. 1 The patient is aligned with the alignment system and four points (M) are marked on the Alpha Cradle^® form (left). To reproduce the “prescribed” treatment portals in the treatment room, the patient must be re-aligned with the alignment system. The internal mammary node field is aligned with the sagittal alignment line. On the right, the patient and the Alpha Cradle^® form are misaligned 5° with the alignment lines. The internal mammary node field is now rotated 5° with respect to the patient.

 

(diagram)

 

Fig. 2 When the patient is rotated only 5° around the sagittal axis (the long axis of the patient’s body), the depth of the tangential fields is different even when the medial field margin is unchanged.

 

POSITIONING DEVICE

    ALPHA CRADLE^® brand Patient Repositioning Systems have been used routinely for positioning patients undergoing radiation therapy for breast cancer in our institution for approximately 15 years. During the late 1980s, a modification was made to include a support for the arm position.¹ The modification consisted of the addition of a handle which the patient can hold onto during the treatment. This modification offers the patient a comfortable resting place for the hand and the elevated arm and also fixes the orientation of the hand during treatment. A reduction in the number of requested treatment field adjustments was noted when the modified ALPHA CRADLE^® form was used but further improvements were desired.

    In patients where a separate internal mammary field was used, the field position with respect to bony anatomic landmarks, primarily the spinal column, was often found to be different from the simulated field when port films were reviewed. It was attributed to the fact that the sagittal alignment line was marked only within the treated segment, i.e., on the chest. It appeared that the entire torso needed to be aligned with the sagittal alignment line in order to correctly reposition the patient (Fig.1). The deep margin of the tangential fields was also frequently different from that which was simulated. This problem was thought to be caused by failure to reproduce the patient’s body rotation around the sagittal axis. The gantry angle was fixed while the patient’s body was rotated differently causing the depth to vary even when the medial beam entry point remained unchanged (Fig. 2). A more aggressive immobilization system was therefore designed in an effort to reduce these errors.

     In most areas of the human body, skin moves over underlying rigid anatomy, causing skin marks to change position with respect to target. This is particularly evident in the breast region where the soft tissues can move several centimeters with respect to the underlying rib cage. We found in other treatment sites, that repositioning the patient in a rigid position device and setting up the treatment to set-up marks on the device, is more reproducible than setting up to skin marks. We therefore designed an ALPHA CRADLE^® form which extends from above the head to the knees, allowing all alignment lines to be marked on the immobilization device.

 

FABRICATION OF THE DEVICE

    The ALPHA CRADLE^® brand Patient Repositioning System consists of a Styrofoam^®* piece, roughly shaped to the part of the patient’s body for which it is intended, glued to an extruded polystyrene base, and a set of bottles containing the foam which, when prepared as directed by the manufacturer, foams up around the patient and forms and mold which tightly fits the shape of the patient’s body (Fig. 3). The ALPHA CRADLE^® form is placed inside a protective polyvinyl bag before the foam is poured inside the form. The patient is then positioned on the bag and the foam expands and fills the space between the patient and the walls of the form.

 

(diagram)

 

Fig. 3 The finished Alpha Cradle^® form fits tightly to the shape of the patient’s body.

 

    All breast patients receiving radiation therapy in our department have a CT scan as part of the treatment planning process. For immobilization we therefore use the ALPHA CRADLE^® BREAST FORM labeled BF4 which has been designed to fit through the tunnel of most CT units. The previously described modification of the ALPHA CRADLE^® form has been extended such that the base is 54” long reaching to just below the knees in most patients (Fig. 4). With the patient in the form, several pieces of Styrofoam^® are placed on the base where appropriate for each individual patient. Marks are made where these pieces need to be fastened and, with the patient removed, they are taped in place (Fig. 5).

 

 

* Registered by Dow Chemical

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(diagram)

 

Fig. 4 The extended breast Alpha Cradle^® form extends from above the head to below the knees. Alignment marks are made on the Alpha Cradle^® form (arrows).

 

(diagram)

 

Fig. 5 Several pieces of Styrofoam^® are taped in place before the foam is poured. A handle for the patient’s raised arm is in a separate small bag above the head.

 

A small triangular-shaped piece of Styrofoam^® is taped to the base of the ALPHA CRADLE^® form under each knee. When the patient’s knees are slightly bent, the lumbar region of the spine becomes relaxed and the patient feels more comfortable. Another piece of Styrofoam^®, approximately 5” x 2” x 1”, is placed between the patient’s knees. This piece increases the height of the foam between the knees where the sagittal alignment line is marked and also helps in making the foam raise up on the medial side of each leg. A 6” high and 1” wide piece of Styrofoam^® is taped to each side of the base to form a barrier for the foam.

    The handle is added by placing a Styrofoam^® cylinder, approximately 3” long and 1” in diameter, into a separate bag which is taped in place under the position of the elevated arm. Several small holes are made in this bag on the side which is toward the ALPHA CRADLE^® BF4-E form so that excess foam can leak out and form a glue which fixes this separate support to the rest of the immobilization device.

    The entire device is then placed inside a protective polyvinyl bag, which is approximately 1’ wider and 1’ longer than the form. The bag is taped down near the chestwall where the lateral tangential field is anticipated to prevent foam from raising more than a couple of inches on the treated side. The absence of foam in this area makes it possible to mark the lateral tangential field on the patient skin surface as well as on the ALPHA CRADLE^® BF4-E form. It also prevents the lateral tangential beam from being intercepted by the foam, which could reduce the skin-sparing effect otherwise observed with high energy beams. Radiation beams entering the skin surface at a steep incline or tangentially provides less skin sparing than a beam entering perpendicular to the surface. Further reduction of the skin sparing by the ALPHA CRADLE^® BF4-E form could, in some cases, cause undesirable skin reaction (SMP always recommends cutting ports in forms. See our attenuation report.).

    One set of AC660 of foaming agents* are prepared as directed by the manufacturer. Approximately 50cc of the foam is poured in to the arm support bag and the remainder is distributed evenly within the form. After approximately 60 seconds, during which time air is allowed to circulate inside the bag, the air is squeezed out, the bag is sealed, and the patient is returned to the form. The patients enter the form by first sitting on the couch near the caudal edge of the ALPHA CRADLE^® BF4-E form and then gradually lift and move the buttocks over the knee supports and into the form. A visual check is

 

* In some cases, another 250 or 375cc of foam may be needed.

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made to see that the patient appears straight on the mold and they are asked to adjust the chest and hips until they feel straight. The patient’s arm is elevated to desired position and the Styrofoam^® handle is moved into the patient’s hand. The foam is pushed up around the hand and the arm. Masking tape, fastened to the sides of the ALPHA CRADLE^® BF4-E form, is placed across the patient’s body to force the two sides in toward the patient’s body to force the two sides in toward the patient’s body to form a tight-fitting mold. Foam is also forced up between the patient’s knees where the sagittal alignment line is later marked.

    A board, which is wider and longer than the ALPHA CRADLE^®

BF4-E form, is placed on top of the couch before the ALPHA CRADLE^® bf4-E form fabrication is initiated to prevent the foam from leaking and forming a lip under the ALPHA CRADLE^® BF4-E form. Such lip or other irregular surface under the ALPHA CRADLE^® BF4-E form could cause a tilt of the ALPHA CRADLE^® BF4-E form and consequently of the patient, giving rise to field misalignments.

    The foam stops swelling after approximately 7-10 minutes but requires approximately 10 additional minutes to become firm. During this time, the patient is asked to think about how it feels to lay in the mold so that when they are repositioned, they can adjust their body until it feels the same.

    To produce a tight-fitting mold, it is important that the patient wears minimal clothing during the fabrication of ALPHA CRADLE^® brand forms. Since patients usually wear different clothing each day during the course of treatment, the mold may be too large some days and too tight on other days. Both situations could compromise the ability to reposition the patient correctly. In patients where the simulation procedure is preceding the CT, the ALPHA CRADLE^® BF4-E form is made in the simulation room, otherwise it is made in the CT room.

 

PATIENT-BEAM ALIGNMENT

    Prior to the simulation procedure it is necessary to have all machine settings (gantry, collimator and couch angles) set to zero degrees. During the simulation procedure, the position of the ALPHA CRADLE^® BF4-E form with respect to the couch is adjusted until the patient’s midline is parallel with the sagittal alignment line. This is determined under fluoroscopy by viewing the position of the patient’s spinal column with respect to the central axis of the beam as the couch is moved along its longitudinal axis. The sagittal line is then marked on the patient’s chest and on the ALPHA CRADLE^® BF4-E form both above the head and between the knees. Since alignment lines frequently are not accurate away from the isocenter, these lines are marked as close to the isocenter as possible by moving the couch along the longitudinal axis.

    The simulation procedure is then carried out in the usual fashion with as much of the set-up marks as possible made on the ALPHA CRADLE^® BF4-E form. Experience from other treatment sites has indicated that these marks are more reliable than skin marks. The internal mammary and supraclavicular fields are usually marked only on the skin surface. The tangential fields are marked on the skin surface while the transverse, sagittal, and coronal alignment lines, indicating the isocenter of the tangential fields, are marked on the ALPHA CRADLE^® form as well as on the patient’s skin surface.

 

PORT FILM REVIEW

    The reproducibility of patient-beam alignment is assessed through weekly port films. Port films are always taken of each field during the first treatment. If no misalignment is noted, the port films are repeated on a weekly basis. If a misalignment is noted, a correction is made and the port film is repeated during the following treatment. To assess the effectiveness of the extended breast form BF4-E, a retrospective review of port films was made. In the review, port films taken of both tangential fields on the same day were recorded as one port film day since it represented only one set-up. Only the physicians’ routine review of port films was used to determine the frequency of misalignments. Small discrepancies between alignment systems in the simulator room and the treatment room and varying amount of sag between the two couches may be the cause of small errors in patient alignment observed on the first set of port films,²⁷ however, in evaluation of the effect of the extended breast (BF4-E) described in this report, all port films were included in the review.

 

PATIENT CHARACTERISTICS

    Thirty-two patients using the extended breast ALPHA CRADLE^® BF4-E forms were treated between 1/93 and 7/93 and have completed treatment. To assess the effect on the set-up reproducibility when the extended breast ALPHA CRADLE^®

BF4-Eform was used, the number of misalignments observed on port films were compared with that of a group of 29 patients treated between 1/92 and 7/92. The earlier group were treated using an ALPHA CRADLE^® BF4-E form which also had a handle for the patient to hold onto during treatment but is extended only to the waist.

    All patients were treated to the breast and/or chestwall using tangential fields. There were 132 port film days in the earlier group and 145 in the group with the extended breast ALPHA CRADLE^®

BF4-E form.

    In the earlier group of patients, 16 had supraclavicular field with 63 port film days while in the group using the extended breast ALPHA CRADLE^® BF4-E form, 13 had supraclavicular field with 57 port film days.

    Fourteen patients in the earlier group, had a separate internal mammary node field with 51 port film days while in the later group only 5 had separate internal mammary node fields in these two groups of patients, it was difficult to make a true comparison of the effect of the modified ALPHA CRADLE^® BF4-E form.

 

RESULTS

    The rate of tangential field misalignments in the earlier group using a short ALPHA CRADLE^®

BF4-E form was 21.2% (28in 132 port film days) while in the more recent group using the extended breast ALPHA CRADLE^® BF4-E form the rate was 10.3% (15 in 145 port film days). The magnitude of the needed adjustment was difficult to assess because the problem appeared to be a combination of translation and rotation errors in most cases. There was no noticeable difference between the two groups.

    Port film review of the supraclavicular field showed that in the earlier group, the error rate was 17.5% (11 in 63 port film days). This increase in misalignments with the long modified ALPHA CRADLE^® BF4-E form is due to 4 misalignments observed in one patient where an anterior supraclavicular field was simulated and initially treated using and SSD technique. This field was later changed to an isocentric technique and an opposing posterior field was added without re-simulation. When these 4 misalignments that are not related to patient positioning are excluded, the error rate is comparable to that found in the earlier group or 14% (8/57).

    A review of the reproducibility of the internal mammary node fields was made but the results are not reliable because of the large difference in number of port film days. In the earlier group of patients, there were 25 misalignments in 51 port film days for an error rate of 49% (25/51) while in the latter group there was only one error in 16 port film days for an error rate of 6.3% (1/16). The results of the internal mammary port film review are very difficult to interpret. One can only surmise that the modified long ALPHA CRADLE^® BF4-E form is superior to the earlier type of breast immobilization since the entire torso of the patient now is immobilized.

    In addition to a reduction in misalignments observed on port films, the patients express a feeling of security and comfort while laying in the ALPHA CRADLE^® form. The arm support and the handle which they hold onto during the treatment prevent straining and thus tiredness. The technologists find it easier and faster to position and to set up the treatment. The reduction in the number of port films is also saving both time and cost.

 

DISCUSSION

    Precision in radiation therapy is critical to the effectiveness of the treatment both in terms of delivery of dose and the coverage of the target. Uncertainties resulting from mechanical machine problems, patient alignment errors, and involuntary motions account for much of the difficulties with reproducing the treatment fields from day-to-day. Increased awareness of these problems has led to the development of the immobilization device described in the report.

    From this retrospective review of port films of these two groups of patients it is clear that the extended breast ALPHA CRADLE^® form improves the accuracy of the set-up although there is room for further improvements. It is difficult to assess the affect on the repositioning of breast patients because of the number of factors that play a role. A field placement error observed on a port film may be due to patient positioning, machine settings, block cutting and mounting, as well as to the compulsion with which the technologists set up the treatment and the physicians review the port films. Some misalignment is more easily observed than others and as a result some misalignments may go undetected. For example, a misalignment on an internal mammary node port film, where bony landmarks (spinal column) can be used for comparison, is easier to detect than an error on a tangential port film.

    The modification of the ALPHA CRADLE^® form described in this report represent only one refinement in the radiotherapy techniques which may have a role in the final outcome of the treatment for patients with breast carcinoma.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Modification of the HS3 Thoracic Alpha Cradle^® For Breast / Chestwall Patients

 

Max Buscher

Tufts New England Medical Center

Boston, Massachusetts

(cover page)

 

A MODIFICATION OF THE HS3 THORACIC ALPHA CRADLE^® FOR BREAST/CHESTWALL PATIENTS

Max Buscher

Tufts New England Medical Center

Boston, Massachusetts

 

 

    The majority of patients needing breast or chestwall irradiation are treated with opposing tangential photon fields. The problem of the sloping chest can be solved by collimator rotation or an angled breast board.

    Collimator rotations of greater than 3° can lead to unacceptable large divergence into the anterior Hockey Stick or supraclavicular fields. This department prefers to angle the patient’s thorax upward to eliminate the slope, i.e., the chest is made horizontal over the length of the tangential fields.

    We have tried various adjustable-angle breast boards and found them unsatisfactory for two reasons. These devices are heavy and cumbersome, as they need to be rigid enough not to sag. This requires they be made from a strong material (wood and plastic have been tried). Secondly, they failed to reproduce the patient’s neck extension and shoulder and arm position.

    A customized and angled immobilizer can be made by modifying the ALPHA CRADLE^® brand HS3 Patient Repositioning System. The shell of this form is shown in Fig. 1 and the inside piece is shown in Fig. 2. It is from this usually discarded inside piece that in inclined plane is assembled.

    This piece is cut into four sections (Fig. 3) using a hotwire cutter. First the head section is cut off and this is then sliced in half length-wise. One half is discarded. The remaining right and left side pieces are each cut diagonally, from top to bottom, to form the right and left sections of an inclined plane.

    Notice that two holes (actually “bites”) are cut in each of the pieces to accommodate the pouring of the chemical – at the shoulders and near the ribs. There will be two pieces left over – the two right and left “tops”. One is discarded and the other is trimmed slightly so it can form the middle section of the inclined plane.

    Fig. 4 shows these pieces assembled into the shell. The three pieces that form the inclined plane should be taped in at the bottom to prevent shifting and leaks. The chemical is poured into the four holes already cut and into the head section. About 1/3 of the chemical should be used in the head area. The whole form is then draped with a mylar sheet and the patient is laid back into it and positioned.

 

(diagram)

 

Fig. 1 The HS3 shell

 

(diagram)

 

Fig. 2 The inside piece.

 

(diagram)

 

Fig. 3 The inside piece modified

 

    When the urethane hardens the mylar is stripped off and a large section is cut from the bottom of the right or left side (Fig. 5) to accommodate skin marking the (right of left) lateral tangential field. About 1 patient in 15 requires more angulation. This can be accomplished by gluing wedges to the base of the form (Fig. 6). We use the urethane foam for this gluing.

 

(diagram)

 

Fig. 4 The pieces assembled back into the shell.

 

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Fig. 5 The poured and finished product.

 

(diagram)

 

Fig. 6 Wedges added for extra angulation.

 

    The cutting preparation described her takes less than ten minutes. We have been using this modified HS3 immobilizer for five years. It is light and provides adequate thorax angulation. It reproduces head position, neck extension and arm position. It has also proven to reduce set up times on the treatment machine.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Utilization of the Alpha Cradle^® For Treatment of the Breast

 

 

Eddie W. Scott, BSRT, RT

Nashville Memorial Cancer Center

Madison, Tennessee

(cover page)

 

 

UTILIZATION OF THE ALPHA CRADLE^® FOR TREATMENT OF THE BREAST

 

Eddie W. Scott, BSRT, RT

Nashville Memorial Cancer Center

Madison, Tennessee

 

 

Over the past twenty years, there have been a great number of improvements in the field of radiation therapy. Since the early seventies, this field ahs acquired the use of sophisticated computed tomography and magnetic resonance scanners to better serve physicians in tumor diagnosis. This field has witnessed the onset of very sophisticated isocentric simulators and planning computers to better potentiate the entire treatment planning process of radiotherapy. The availability of these diagnostic and therapeutic tools have made it possible to achieve a high degree of precision in the field of radiation therapy.

    Although there are many new tools that offer new approaches to precision radiotherapy, one weak link that poses a threat to the overall treatment planning process is the problem of patient positioning.

    Regardless of how modernized and sophisticated our diagnostic and therapeutic tools are or how knowledgeable our radiation oncologists are, if the daily treatment cannot properly be administered, then all is to no avail. Therefore, correct patient positioning is critical and must be viewed as such by the radiation therapy technologist.

    In this field, patient positioning is crucial. For the proper treatment to be delivered, it is necessary that the patient be placed such that the exact position can be maintained and reproduced each day. The quality of patient care provided by the radiation therapy technologist is dependent upon precisely administered treatments. Therefore, optimal treatment requires a conscientious daily effort to minimize any variations from the selected treatment plan.

    Through my experiences over the past several years, I have found that by using the ALPHA CRADLE^® brand Patient Repositioning Systems from Smithers Medical Products, Inc., the risk of error due to patient positioning is greatly reduced. I have used ALPHA CRADLE^® forms as an aid to treat various parts of the anatomy. Set-up for the breast and chestwall regions is enhanced by the use of the cradles. The ALPHA CRADLE^® form is a simple tool that is commonly used in many institutions for treatment to this region of the body. By using the ALPHA CRADLE^® brand form I have found that it enables the technologist to duplicate the daily treatment with much consistency.

    The breast or chestwall patient can very often be difficult to obtain correct positioning. Radiotherapy of the breast and adjacent nodes involves the most complex geometric and field matching situation for the average radiation oncology department. The treatment position for the patients with breast carcinoma varies somewhat depending on the treatment technique employed. It should however, remain the same during the entire course of treatment and during the treatment of each field each day. Once positioned in the ALPHA CRADLE^® Patient Repositioning System each day, the patient’s position should remain constant until the treatment is complete.

    The basic technique for the treatment of breast carcinoma is opposed medial and lateral tangential fields directed across the chestwall or breast and in many cases an anterior field to include the supraclavicular an axillary lymph nodes. The inferior field border of the supraclavicular field should be matched against the superior field border of the tangential field to avoid an underdosage in the area between the two fields. Some physicians choose to use a small gap between these two fields to prevent an overdose or hot spot to this region.

    Achieving coincidence of these three diverging beams is a problem never easily solved. When treating the small breast one may find that it is quite easy to get field sizes to coincide and field borders to match and line up correctly. On the other hand, treating the large pendulous breast often requires manipulation of the upper thorax and arm to properly align fields.

    It cannot be over emphasized the importance of NOT overlapping the tangential and supraclavicular fields. The ALPHA CRADLE^® Patient Repositioning System which provides a great deal of stability for this particular treatment set up, is the most effective tool in controlling this problem. Since the ALPHA CRADLE^® form is formed to the patient’s contour, it allows for minimal involuntary movement of the patient’s body. This enables the technologist to duplicate each field daily with very little discrepancy. By using the ALPHA CRADLE^® form for this treatment, I have found the consistency of this treatment set up to be unmatched by other methods.

    The ALPHA CRADLE^® form is prepared for this technique just prior to the simulation process. Upon pouring the foaming agents in the ALPHA CRADLE^® liner, the foam will begin to rise and proceeds to inflate the polyform bag in the position that the patient is to be treated in each day. This now allows the mold to conform to the contour of the patient’s body. After the mold has hardened, the field parameters are set and measurements are taken with the patient being in what is now the actual treatment position. This now allows for consistency between the simulation table and the treatment couch.

    Both the chestwall and the breast setup requires extension of the arm for entry and exit of the radiation beam. The arm position must be reproduced each day since skin marks move over underlying tissue as the arm position changes. By using the ALPHA CRADLE^® form, this problem is eliminated. The ALPHA CRADLE^® form forms a hardened foam resting surface below the shoulder and extending the numeral shaft. This allows for the shoulder and arm to be in the exact position each day. This, in turn greatly enhances the match line accuracy between the tangential and supraclavicular fields. The ALPHA CRADLE^® form eliminates the need for using an armrest to extend the arm away from the torso. Unlike an adjustable arm rest, the ALPHA CRADLE^® form allows for much greater precision in the treatment since the arm is lying in a flat pre-molded cast rather than hanging from an adjustable bar that allows the elbow to swing freely. This will provide more consistency in aligning the supraclavicular – tangential match line.

    This junction line between the supraclavicular and tangential field is a very critical region. The treatment to this area must be precise in order to prevent ‘hot’ or ‘cold’ areas as this junction site. By using the ALPHA CRADLE^® Patient Repositioning System, this problem is virtually eliminated. Since the patient’s arm is placed in a premolded form, no change in the arm position will likely occur from day to day.

    The thorax which rests flatly in the ALPHA CRADLE^® form is also in a very comfortable and stable position. The thorax is held secure on each side by the hardened ALPHA CRADLE^® form which has inflated to create a rim-like wall on each side of the upper torso. Therefore, lateral movement of the thorax is not possible while in the ALPHA CRADLE^®. However, the technologist must be careful to assure that the patient is lying flat in the form during simulation when the ALPHA CRADLE^® form is being formed.

    On occasions, treatment plans for breast of chestwall patients will include a boost (an additional radiation field) to the posterior axillary region. If this is indicated, modifications can be made to the ALPHA CRADLE^® form without causing any effects on the patient’s position. In this instance, a small opening can be cut out just over the auxiliary region. This will allow a posterior radiation beam to treat the axillary nodes without attenuation from the ALPHA CRADLE^® material.

    Many physicians prefer using a breast board as an aid in treating this region of the body. The breast board is basically an angle board that the patient lays on to level the upper and lower chestwall. This technique can be used very successfully in treating breast and chestwall region. However, for this technique there are several variables that make reproducibility each day difficult (i.e. obtaining the exact position on the breast board each day). The ALPHA CRADLE^® form does not reduce the slope of the chestwall as nicely as does the breast board. However, it compensates for this in reproducibility, stability, and patient comfort. Many physicians who prefer the breast board have not had the opportunity to use the ALPHA CRADLE^® form and experience their versatility.

    Many institutions use elaborate casting techniques to immobilize patients during treatments. Some of these techniques have been quite effective in minimizing patient motion. However, patients are known to move within a cast especially if the fit is not good. One of the benefits to using the ALPHA CRADLE^® form is that the hardened rim that forms the top and sides of the cradle secure the patient from moving in any direction. Another advantage is that after lying in the ALPHA CRADLE^® form for a few treatments, the patient will be able to tell if they are in the correct position within the ALPHA CRADLE^® form.

    The ALPHA CRADLE^® form does provide a great deal of stability for the breast and chestwall set up. It can also be used very effectively for other treatment set ups (i.e. mantles, head and necks, and extremities).

    There are many different immobilization techniques that are used for treatment of the breast and chestwall region. I have found the most effective of these methods are those in which the patient is positioned lying relaxed and comfortable. Some treatment set ups for the breast region place the patient in cumbrous positions which often results in an ineffective treatment plan.

    I feel the ALPHA CRADLE^® Patient Repositioning System meets the needs for all involved in the treatment of carcinoma of the breast. It provides the technologist with security in knowing that the treatment set up is correct. It helps provide the physician an optimum treatment plan for the breast region and it provides the patient a stable and comfortable resting surface in which to be treated.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alpha Cradles^® in Breast Cancer Treatment

 

 

Susan Hook, RTT

Jane Pardy, RTR

Boston, Massachussetts

(cover page)

 

 

ALPHA CRADLE^® BRAND FORMS IN BREAST CANCER TREATMENT

Susan Hook, RTT

Jane Pardy, RTR

Boston, Massachusetts

 

INTRODUCTION

    The treatment of breast cancer with radiation has always been a process that required a great deal of accuracy and consistency in patient set up. Today the treatment of choice for early stage breast cancer is biopsy or lumpectomy plus radiation therapy and/or chemotherapy. We are, therefore, seeing many different types of treatment volumes.

    With the recognition of radiation therapy as an alternative, we are seeing those patients who are not good physical candidates for surgery. These patients are thus challenging in so far as they require an accurate daily set up.

 

TECHNIQUE

    The simulation of the isocentric technique used in our department requires the patient to maintain her position, supine on a 21° angle board with her arm extended 90° or more from her body with her hand on her head. When this technique was first introduced, we found that few women were able to maintain this position. We then realized how much an individualized immobilization device was needed.

    Our technique is very simple. Using ALPHA CRADLE^® brand AC325, we shape the bag to fit the patient. We then pour the foaming agents and allow them to begin to rise before lying the patient down. We explain in detail the procedure to the patient and the need for us to move quickly. The patient lies down and we adjust the bag; with two sets of hands, we can shape the bag to suit our specific needs.

    Once set, the ALPHA CRADLE^® form was modified to allow set up equipment to be attached to the simulator and treatment couch. The contour was taken with the cast in place. The simulation time was a lengthy 1-1/2 hours. However, the patient was still comfortable at the end of this time and the technologist felt assured that she had remained still.

    Patient B was a 57 year old white female with intraductal in situ carcinoma of the right breast with a complex history which made her medically inoperable. This lady had extensive cardiac disease as was status post left CVA with right hemiparesis which made her body positioning more challenging.

    Using two sets of AC325 FOAMING AGENTS, we were able to mold the chemical around her abducted right arm to give it the extra support which she needed to maintain her position. The cast also made her feel comfortable and relaxed which allowed us to proceed with the simulation and eventual daily treatment. She was treated with two tangential fields to the right breast.

SUMMARY

    We have adopted the slogan “No breast patient is too difficult to immobilize using AC325 FOAMING AGENTS.” These casts have allowed the patient to be in a comfortable position for a rather long and sometimes arduous simulation process. It also makes the patient feel that we as professionals have done the most we can by providing and individualized service.

    From the technologist’s point of view, the cast enables us to focus on our jobs of accurate measurements, good simulation and sets the scene for good patient interaction, which is especially important for cancer patients. The cast provides a light, easy-to-make customized immobilization device that allows the patient to be treated quickly and accurately each day.

    Because the molds have become so popular with patients and technologists, it is now our policy that all patients treated for breast cancer are simulated and treated in an ALPHA CRADLE^® device.

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alpha Cradle^® Brand Patient Repositioning Systems for Intact Breast Patients

 

 

Janet Protesto, RTT

Bethesda Memorial Hospital

Boynton Beach, Florida

(cover page)

 

 

ALPHA CRADLE^® BRAND PATIENT REPOSITIONING SYSTEM FOR INTACT BREAST PATIENTS

Janet Protesto, RTT

Bethesda Memorial Hospital

Boynton Beach, Florida

 

 

    With the advent of lumpectomy and the preservation of patient’s breast, a variety of treatment techniques have arisen. Most radiation therapists have worked with the breast ramp, a cumbersome device to say the least. Securing the ramp to the treatment table is of great concern.

Patient positioning on the ramp can also be quite exasperating. Frequently patients will slide down the ramp to where they are most comfortable. This technique also involves using a heavy half-beam block. With the introduction of the ALPHA CRADLE^® brand Patient Repositioning System to our department, we have achieved the following:

1)    Elimination of SSD and introduction of SAD technique

2)    Elimination of the breast ramp

3)    Elimination of the half beam block

4)    Assurance of accurate and reproducible set ups

5)    Cat Scan localization films taken with the patient in the treatment position

 

    Simulation procedures are simple and consist of two parts. The making of the ALPHA CRADLE^® form and the CT scan localization make up the first part of the simulation procedure. The second simulation is the taking of films.

    Since patients vary in age, differences in breast tissue also occur. To compensate for these differences, angle sponges and Styrofoam^® are used to assist in making the cradle.

    While patients with small breasts appear to need a slight angle to elevate the chest, a small angled piece of Styrofoam^® may be placed on the cradle board under the ALPHA CRADLE^® form. The patient is then positioned on the board for proper alignment. While the form is being made, careful attention is given to cover all the Styrofoam^®. This allows removal of the Styrofoam^® and still achieves the necessary angle of the chest for daily treatment. At this time attention should also be given to the affected arm. This ALPHA CRADLE^® form must give proper support to this arm to keep it secure during treatment.

    Large breasts present a few problems. If a patient with a large breast lies flat on the ALPHA CRADLE^® board, the superior aspect of the breast may rise into the supraclavicular region. Steep

angled Styrofoam^® blocks will be added to elevate the chest. Positioning is extremely important before the ALPHA CRADLE^® form is made. If the breast sags laterally an angle sponge may be used to rotate the patient slightly. These problems should all be addressed before the ALPHA CRADLE^® form is made. The physician, dosimetrist and the therapist must decide on the proper placement to the Styrofoam^® and angled sponges before the ALPHA CRADLE^® form is made. Only after these factors have been attended to can construction of the ALPHA CRADLE^® form begin. If an angle sponge and Styrofoam^® blocks are being used in the positioning of a large patient then an adult and pediatric foaming agent set are mixed together. This allows more support to the back, neck and affected arm of the large patient. As an extra measure, lateral laser marks may be placed on either side of the abdomen.

    Patients are then escorted to the CT scan department. The localization films are taken while the patient lies in the ALPHA CRADLE^® form in the treatment position. The dosimetrist then plans the treatment planning will give the therapist the field size and gantry angles that will be used during the second simulation.

    The second simulation procedure will go very smoothly. Patients will find it very uncomfortable if they do not fit into the ALPHA CRADLE^® form properly. Rarely is there a case when a simulation film or gantry angle must be changed. Initial films on the treatment table as well as weekly port films are accurate and the therapists are very confident with the daily set ups.

    Quality of the treatment is most important to achieve the desired effect and the ALPHA CRADLE^® forms are an important contributing factor. Preparation for breast patients using ALPHA CRADLE^® forms is time consuming but the rewards are well worth the time. Accuracy, speed and reproducibility are the key factors for using the ALPHA CRADLE^® forms.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Technique for Evaluating Cast Foam Positioning and Immobilization Devices Used in Breast Cancer Radiotherapy

 

 

Kent McCune, RTRT, CMD

Linda Parsons, RTT

Linda Schoenfeld, RTT, CMD

Anne Maddeford, BSRT, RTT

 

 

A TECHNIQUE FOR EVALUATING CAST FOAM POSITIONING AND IMMOBILIZATION DEVICES USED IN BREAST CANCER RADIOTHERAPY

Kent McCune, RTRT, CMD

Linda Parsons, RTT

Linda Schoenfeld, RTT, CMD

Anne Maddeford, BSRT, RTT

 

 

INTRODUCTION

    The treatment of primary breast cancer with excision plus radiation is becoming an accepted alternative to mastectomy for localized breast cancer.^{1,7,13,14,18,19} The use of conservative surgery and radiotherapy is based on studies demonstrating local control and survival comparable to those achieved with mastectomy.¹⁸ Minimizing the risk of normal tissue damage while delivering a dose distribution that will result in a high level of local control is the goal of radiation therapy. A three or four field technique is commonly used for radiation therapy of breast cancer when the patient has positive axillary nodes. The breast, chest wall and ipsilateral internal mammary nodes are generally irradiated with two opposing tangential fields. The third field irradiates the supraclavicular and axillary nodes and is angled fifteen degrees from the vertical to avoid the esophagus and spinal cord. The fourth field is 180° opposed to the scf/axilla field and irradiates the axilla only. Treatment techniques for field matching in primary breast irradiation have been described in detail.^5,6,16 Matching fields in such a complex treatment requires precise positioning and immobilization of the patient to prevent overlapping treatment fields. Lack of patient immobilization will greatly increase the probability of field overlap. Litcher et al have studied the dosimetry at the matchline between the supraclavicular and tangential fields.¹¹ Roberson et al have studied the amount of lung which is irradiated by various methods of treatment of the internal mammary nodes.¹⁵

    Doses to the contralateral breast and the influence of lung density corrections on treatment planning for primary breast cancer have been investigated by Fraass et al.⁹ Bentel has studied port films of patients receiving radiation therapy for carcinoma of the breast utilizing a modified ALPHA CRADLE^® brand BF2 positioning and immobilization device.² This study was based on the review of port films only. Careful review of the treatment portal films is the only way to check the adequacy of the radiation fields to the target volume.^4,8 The review of port films does not help to solve the difficulties arising from patient movement during treatment, or the difficulty of accurately reproducing the patient position relative to the beam, from one treatment session to another.⁸ We feel the review of port films alone in the treatment site is not a reliable indicator of how precisely the ALPHA CRADLE^® form is reproducing the patient position. Our goal was to quantitate how accurately the original patient position relative to the ALPHA CRADLE^® form was being reproduced. To date we are not aware of any study quantitating the reproducibility of patient position relative to a cast foam immobilization device. The objectives of this present study are to: a) Quantitate the reproducibility of patient position relative to a modified HS2 ALPHA CRADLE^® form, b) give us a means to evaluate different ALPHA CRADLE^® forms, c) develop guidelines and recommendations on how to most effectively use the ALPHA CRADLE^® forms, d) justify to the hospital the extra time and staff required to make the patient immobilization devices.

 

METHODS AND MATERIALS

History

    For primary breast cancer radiation therapy, generally the patient position is supine with head turned slightly to the contralateral side of the effected breast, and ipsilateral arm positioned on an armboard. It became apparent through the review of treatment portal films that the reproducibility of the prescribed fields was not accurate. Reviewed port films revealed that often the arm position was incorrect and tangent fields would not be reproduced to include the entire chestwall. The radiation therapists were asked to make an assessment of the reproducibility of the breast set ups. The information provided by the therapists reveled that the breast set ups were cumbersome, time consuming and patients often had to be repositioned in between fields to reproduce the correct set up. In order to correct these problems and eliminate the need to re-simulate patients, a method of positioning and immobilization using the Smithers ALPHA CRADLE^® Patient Repositioning System was chosen.

    This institution had no prior experience using ALPHA CRADLE^® Patient Repositioning Systems in breast set ups; therefore a technique was developed to evaluate and quantitate how accurately a patient’s position could be reproduced. We utilized the ALPHA CRADLE^® MOLD MAKER system, the standard HS2 ALPHA CRADLE^®, and our custom modified HS2 ALPHA CRADLE^® in this study. The MOLD MAKER system utilizes a bag and chemicals to generate a custom immobilization and repositioning device for the patient. The standard HS2 cradle in contrast, uses a pre-fabricated form that positions both arms up 45°.  We extensively modified a standard HS2 ALPHA CRADLE^® due to the preliminary findings of this study. The modified HS2 ALPHA CRADLE^® positions both arms up 60°. Positioning both arms up enables: a) a three point set up on the lower thorax, b) provides symmetry to breasts, c) facilitates an accurate CT set up, d) correct treatment position for those patients which return for contralateral breast irradiation. The ALPHA CRADLE^® form’s base and sides have been lengthened six inches to provide support, and to correctly position the lower thorax for treatment. The superior end of the form also positions and immobilizes the head to reduce the chance of treating the spinal cord and esophagus on those patients with a supraclavicular field.

 

ALPHA CRADLE^® FORM PREPARATION

    The ALPHA CRADLE^® forms are prepared as directed by Smithers Medical Products, Inc., i.e. the protective sheeting secured with tape, chemicals shaken mixed, shaken and poured, the patient placed in the form. Before the foaming agents begin to foam, the patient is maneuvered under the simulator gantry and positioned for visual anatomical straightness. Then using fluoroscopy the patient is aligned so that the spinous processes are coincident with the longitudinal axis of the projected central axis of the X-ray beam before the mold hardens. Reference marks are placed on both sides of the form and the patient to indicate the transverse laser location. The patient is now indexed to the form in the longitudinal plane. Next the patient sits up and out of the form so that the side of it can be cut away to visualize the entrance of the lateral tangent field. Then the patient lies back into the form and the patient and form are adjusted so that all reference marks lie in the same transverse plane and are coincident with the transverse lasers of the simulator. Simulation is then completed, localizing the tangent fields along with the nodal areas to the physician’s prescription.

After the fields have been approved, patient positioning marks are added. Our institution has chosen to locate a mark on the anterior midline in a transverse plane that encompasses the inferior border of the tangent field. Marks are also placed on the patient’s right and left, in the same plane at a specified depth. The anterior mark will follow in a sagittal line with the set up point for the tangent fields. A third point is placed at the superior edge of the tangent fields. These positioning marks are used to reproduce the longitudinal axis of the treatment set up. Additionally, the form alignment marks are positioned to lie in the same transverse plane as the anterior set up point of the tangent fields.

    With the patient and modified HS2 form marked, the patient sits straight up. Four millimeter lead sphere markers are positioned and embedded in the ALPHA CRADLE^® form coincident with the projected central axis of the X-ray beam. One marker at the central axis, another approximately 8-10 centimeters superior, inferior, right and left of the central axis. The markers are then covered with masking tape and the central axis lines drawn on the bottom of the form. The patient is then repositioned in to the ALPHA CRADLE^® form and all positioning marks are checked and realigned if necessary.

    With the gantry positioned to direct the X-ray beam vertically down through the set up point for the tangent fields, one additional film is exposed. This film will record the anatomical position of the patient in relationship to the ALPHA CRADLE^® form and central axis of the X-ray beam. On the first day of treatment, a port film is recorded with the X-ray beam directed vertically down through the set up point for the tangent fields. This film is recorded with a Port Film Marker* in place. The port film marker registers the location of the transverse and longitudinal axis of the X-ray beam on film, and also provides a means to determine the source film distance of the film. An additional film is taken midway through the treatment course.

 

* Registered by Northwest Medical Physics

(bottom of page)

 

RESULTS

    Preliminary results using the MOLD MAKER system and the unmodified HS2 ALPHA CRADLES^® indicated that several problems were occurring with regard to patient set up reproducibility: a) the form was often skewed, b) the central axis of the X-ray beam was not coincident with the central axis indicated by the lead markers in the form, c) the patient’s position relative to the ALPHA CRADLE^® form was not being reproduced in the inferior portion of the field. These problems were corrected by: a) placing thirty-six by two inch strips of Velcro^® Loop on each side of the simulator and treatment tables and six inch by two inch wide Velcro^® Hook on each corner of the ALPHA CRADLE^® form’s base to secure the form to the table, b) instructing the therapist to align the central axis of the X-ray beam to the marks in the ALPHA CRADLE^® form before the patient is positioned into the form, c) utilizing the modified HS2 ALPHA CRADLE^® to correctly position the lower thorax for treatment. This eliminates the skewing of the form, the noncongruence of the central axis, and allows for patient adjustments without disturbing the form’s alignment to the X-ray beam.  

    The analysis of eight cases utilizing the modified HS2 ALPHA CRADLE^® proceeded as follows: For each reference simulation film a number of spinous processes were not adequately visualized, rib facets were used as the reference bony landmarks. These landmarks were selected for their visibility and for their stability. The same landmarks were then identified on the treatment machine portal films. Measurements of the distance between the reference landmarks and longitudinal axis were done on both the simulation and treatment portal films. Alignment was judged on the position of the spinous process bony landmarks on the treatment machine portal film relative to the reference simulation film. Table 1 gives a summary of those measurements. Column 1 is the number of reference landmarks used in each case. Column 2 is the mean distance to the landmarks as measure on a line perpendicular to the reference longitudinal axis. Column 3, the mean set up error, is a measure of the difference between the reference landmark

location on the portal film relative to the simulation film.

   

DISCUSSION

    Radiation therapy seeks maximization of the probability of local tumor control and minimization of the risk of significant complications. As the ability to accurately define the target volume improves, tighter margins are placed on the target volume to help decrease morbidity associated with treatment. The margins selected between the treatment volume and the target volume must reflect the uncertainty in the definition of the tumor volume, the possibility of patient motion, the proximity of radiosensitive structures and beam penumbra. Accurate field placement is essential if maximum tumor response is to be achieved with minimal morbidity.^8,17 The importance of immobilization for the accurate delivery of radiation to a target volume is well documented in the literature.^10,12,17 To reproduce the patient position and to minimize patient movement during treatment the immobilization device must be supportive and comfortable. The therapists are instructed to align the longitudinal and transverse planes with the laser positioning lights to help ensure the reproducibility of the position. The ALPHA CRADLE^® device will aid in positioning and immobilizing the patient, but it is still up to the radiation therapists to reproduce the correct patient position on a daily basis. Feedback from the therapists as well as personal observation of daily set ups confirms that minimal adjustment of the patient position is required once the patient lies back into the modified HS2 form. The therapist also states that there is no patient movement observed during treatment. As a result, patient treatments are being delivered with a greater degree of accuracy, the ease of set ups has improved, and the set up times on the machine have been reduced.

    A diagnostic quality reference simulation film imaging the vertebral column and spinous process is critical to the success of this technique. The major drawback with this procedure is the poor definition and visualization of the reference anatomical landmarks on the treatment portal film. An imaging enhancement system would be very beneficial to this technique. To maximize imaging of the anatomical references on the treatment portal we use 3M XL* simulator film in lead screened cassettes. In addition, the therapists are instructed to position the collimator settings to that of the tangent fields for the first exposure, and full field for the second exposure. To fully realize the effectiveness of an ALPHA CRADLE^® form, we recommend the following guidelines be adhered to: a) utilization of Velcro^® or some other device to secure the ALPHA CRADLE^® form to the simulation and treatment table, b) mark the projected simulator central axis cross hair location in the ALPHA CRADLE^® form, c) align the ALPHA CRADLE^® form to the treatment machine before patient lies back into the form, d) not manipulate form to align patient to treatment machine, position patient within the form coincident with the X-ray beam axes. Using these guidelines and the 4mm lead marker technique, we were able to evaluate the effectiveness of the ALPHA CRADLE^® form and quantitate how accurately a patient’s position could be reproduced. On the average we were able to reproduce the original patient position to within 0.16 cm. Localizing the original reference longitudinal axis with 0.16 cm does not guarantee that the treatment fields will be reproduced within that same magnitude. To determine the adequacy of the radiation fields to the target volumes requires careful review of the treatment portal films. We feel this technique when used in conjunction with the careful analysis of the treatment portal films is very useful in determining the accuracy of patient repositioning, the effectiveness of the ALPHA CRADLE^® form, and precise field placement.

 

*Registered by 3M Corporation

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    We recommend that other institutions use this technique and guidelines to evaluate their form’s performance due to the variation in the construction and use of ALPHA CRADLE^® forms. This is an excellent quality assurance procedure that can be easily implemented as deemed necessary to ensure the effective use of an ALPHA CRADLE^® device.

 

(diagram)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER FOUR

 

 

REPOSITIONING AND IMMOBILIZING THE PROSTATE PATIENT

(cover page)

 

ALPHA CRADLE^® PATIENT REPOSITIONING SYSTEMS:

PF1, PFM, BB

    Two of the three shells offered for treatment of prostate cancer have recently been developed. These new forms allow the patient to be treated in the supine (Pelvic Form Modified) and the prone (Belly Board) position. The belly board makes allowance for a cutout section which allows the bowels to drop, minimizing the amount of small bowel in the treatment field. The new modified pelvic form immobilizes the patient from the base of the ribs to the bottoms of the feet. Triangular supports fit under the knees while the base end controls flexion of the feet. These new forms allow the medical professional to use a customized repositioning tool whether they treat their patients in the prone or supine position.

    All of the customized forms developed for use in treating patients with cancer of the prostate have unattached pieces that must be attached by the medical professional before the fabrication of the form can begin. It is important to measure the width of the patient and attach the side piece allowing no more than one inch between the side of the mold and the patient. This is the secret for creating tight fitting forms. By placing the side rails too far from the patient, the foam will not rise sufficiently to provide the immobilization needed for this larger form.

    If using the modified pelvic form, you must use 2-3 people to create the form. The extra sets of hands are necessary to shake all of the sets of foam at one time and to keep the rising foam tight against the patient’s skin. If possible, you need to have the patient lay in the empty shell so you can accurately mark on the base where the side rails, knee supports and base piece should be connected with double-sticky tape, already attached. If you cannot have the patient lay inside of the empty shell, you can measure the patient and approximate the positions of the pieces. To get good formation around the patient’s legs, pour the foam slowly over the knee supports and then the rest of the form. Save some foam so that you can reapply a second coat of foam on top of the first coat. This double coating will provide you with ample foam once it begins to rise around the patient’s legs. The empty bottles and lids can be place inside of the form between the two knee supports. This will displace more foam that can be better utilized foaming around the patient’s anatomy. If you do not want to place the empty bottles inside of the form, pieces of cut polystyrene can also be used to displace the foam between the knee supports. As the foam starts to expand, pull the bag of sheeting up between the patient’s legs. This will allow ample foam to form between the patient’s legs. As the foam begins to feel spongy, place the foaming agents as firmly against the patient as you can. 

    This will make a firm guide for future use of the form. As extremities tend to rise out of the forms, remember to apply pressure to the feet unless you’re sure your patient has an extremely well developed sense of humor!

    When using the belly board for prone positioning, you will need to measure the distance that the patient is raised from their pubic bone to the treatment couch when their belly is allowed to just touch the treatment couch. This will determine the height of the center pieces that are affixed to the base with tape. Be sure that when you attach the side rails, you only allow one inch of space between the rail and the patient. Allowing more space reduces the height of the foam needed to make an effective form. After completion of the form, cut a port through the base, further allowing the belly to drop from the treatment field. Remember to wipe the form clean with a damp cloth removing any particles of foam that may have accumulated. Next, cover the exposed areas of foam with a paper of cloth tape. This will prevent the patient’s skin from becoming irritated from contact with exposed foam.

    ACMMII

    The ACMMII allows you to create prone or supine forms for your patient. The most beneficial tip when making effective prostate forms is to make sure the base is strong and durable. Due to the nature of the form, this form seems to receive more abuse from patients getting in and out of the form than most others. To increase the stability of the base, take a 1” thick piece of extruded polystyrene (the blue boards) and cut a piece 10”x 12”. Place this piece inside of the bag of foaming agents, pouring the foam around the inserted piece. As the foam rises and expands, it will bond to the inserted base piece creating a very strong and durable foam.

    When making the form on your patient, take the recapped bottle marked #1, and carefully place it underneath the bag of foam between the patient’s legs and slide it up until it makes soft contact with the patient’s groin. This will assist the bag of rising foam make a good impression of the patient’s inner leg. This will also allow you to keep the bag of foam high in relative position to the patient’s legs. Don’t be afraid to grab the bag and pull it up if you’re not getting enough foam between the patient’s legs. As the foam begins to harden, place the remaining dividers between the dividers that are in place and the bag of foam. This process will keep the foam tight against the patient as it hardens.

    Ports are easily cut into the base of sides as needed. Remember to clean the form of debris when cutting ports, and cover the area completely with cloth or paper tape. The forms should be indexed with a marker in conjunction to the relationship of the form with the lasers. This will allow you to return the form to its original position for each successive treatment. If your patient is obese, a small series of tattoos can be placed on the patient’s skin where they meet the cradle. This will allow you to rotate the patient’s skin back to the original position.

 

Stabilization Device for Patients Undergoing Prostate Irradiation

 

 

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

STABILIZATION DEVICE FOR PATIENTS UNDERGOING PROSTATE IRRADIATION

By Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

 

INTRODUCTION

    Bladder and bowel toxicity associated with prostate irradiation is well documented and methods to reduce the frequency and severity of these toxicities have been studied. Conformal therapy techniques, where treatment fields are designed to conform to the target while limiting the volume of bladder and rectum in the beam’s-eye-view, has shown to reduce the morbidity in prostate irradiation.^3,4,10,13,14 Prostate irradiation using small target margins, however, should not be undertaken without effective patient immobilization. ^1,12

    In early 1992, a three-dimensional treatment planning system (Virtual Simulator*)¹¹ was phased in to clinical use in our department. The tumor margins in patients with prostate carcinoma undergoing three-dimensional treatment planning were frequently smaller and we therefore began using ALPHA CRADLE^®** brand Patient Repositioning Systems for these patients in an attempt to improve set up accuracy.

 

IMMOBILIZATION DEVICE

    The prostate ALPHA CRADLES^® PF-E, which extend from the mid-chest to below the feet, consist of a Styrofoam^®# form which is filled with foaming agents that expand and form a mold around the patient. The base of the ALPHA CRADLE^® form is a Styrofoam^® sheet approximately ¾” thick, 6’ long and 2’ wide. With the patient on the base, several pieces of Styrofoam^® are added to make the mold comfortable and sturdy (Fig. 1). The patient’s knees are bent to relax the lower back and a triangular-shaped piece of Styrofoam^® is placed under each knee to support the position. A piece of Styrofoam^® is added on each side and below the feet as close to the patient as possible. With the patient removed, the excess width of the base plate is cut away and the entire Styrofoam^® form is placed inside a polyvinyl bag. This bag must be considerably wider and longer than the base plate to allow space for the foaming agents to expand up along the patient’s sides and between the legs and feet. Approximately 660 to 975cc of foaming agents are prepared as directed by the manufacturer** and are evenly distributed inside the form. Air is allowed to circulate inside the bag until bubbles are noted in the foam (1-2 minutes). The air is then forced out, the bag is sealed, and the patient is returned to the form. The patient enters the form from the head of the couch and gradually moves into the form until the knees are in proper position on the knee supports. The patient must adjust the chest, hips, and legs until he feels straight and the staff make a visual check that he appears straight. All clothing under and on the sides of the patient is removed allowing the mold to form to the skin surface. The excess width of the bag of pulled in toward the space between the patient’s torso and the Styrofoam^® sides as well as between the patient’s legs allowing the foam to expand and form a tight mold to the patient’s torso and each side of both legs (Fig. 2).

 

* Sherouse Systems, Inc.

** Registered by Smithers Medical Products, Inc.

# Registered by Dow Chemical

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(diagram)

 

Fig. 1 Stryrofoam^® barriers are taped to three sides to prevent foam from leaking. A triangular Styrofoam support for each knee is also taped in place before placing the entire form in the polyvinyl bag.

 

    Occasionally, form may leak and form a lip over the couch, causing an irregular surface under the ALPHA CRADLE^® form. To avoid having an irregular surface under the finished mold, the ALPHA CRADLE^® form is built on a hardboard that is wider than the base of the mold. The process of building this ALPHA CRADLE^® form requires approximately 45 minutes.

 

ALIGNMENT MARKS AND TREATMENT

    ALPHA CRADLE^® forms are made for all prostate patients undergoing three-dimensional treatment planning in our department. The ALPHA CRADLE^® forms are therefore made in the computed tomography room immediately prior to obtaining the CT based data set. Reference marks are made on the patient and on the ALPHA CRADLE^® form to establish the coordinates for the Virtual Simulation. Laser alignment systems are used in each room to help reposition the patient. Alignment marks are made both on the ALPHA CRADLE^® form and the

 

(diagram)

 

Fig. 2 The Alpha Cradle^® forms a tight mold for the legs and the pelvis. The foam is forced up on each side of the patient’s legs, hips and chest. Repositioning marks are made on the Alpha Cradle^®.

 

patient’s skin, however, since skin tends to move with respect to deeper tissues, the marks on the rigid ALPHA CRADLE^® form are considered more reliable, in the case of a discrepancy. Motion of skin marks with respect to deeper tissues is more pronounced in areas where there is a thick layer of subcutaneous soft tissues. Tightening or relaxing a muscle also causes the skin to move with respect to deeper tissues, and in some situations, the skin is pulled in one of the other direction as the patient lies down. Another problem with skin marks is that they tend to fade and are therefore reinforced several times during a course of treatment. It is possible that each time the marks are reinforced, they are placed a little to one side, and over a period of time they could migrate, giving rise to a field shift. The problems with migrating marks are avoided when the marks are made on the ALPHA CRADLE^® form. When the patient is repositioned correctly in the ALPHA CRADLE^® form, the marks on the ALPHA CRADLE^® form are fixed with respect to the patient, and since the marks on the ALPHA CRADLE^® form do not fade or wear off, eliminating re-marking, they do not migrate.

    The sagittal alignment line is marked on the skin of the pelvis and on the mold from between the patient’s thighs to below the feet (Fig. 3). A lateral (horizontal) alignment line is marked on each side of the ALPHA CRADLE^® form. One transverse line is marked on the pelvic skin an extending onto the ALPHA CRADLE^® form. A second transverse line is marked on the skin just below the knees where the skin moves very little compared with that in the pelvic area. The second line, which also is marked on the ALPHA CRADLE^® form, is used to assure that the patient is repositioned correctly in the ALPHA CRADLE^® form in the cepahlad/caudal direction.

 

(diagram)

 

Fig. 3 Set up marks are made on the Alpha Cradle^® form and on the patient. The transverse line across the calf of the legs (arrow) are used to assure that the patient is positioned correctly in the cephalad-caudal direction.

 

    The majority of patients are treated using a 4-field box technique. The position of the isocenter with respect to the coordinate system is marked on the ALPHA CRADLE^® form and on the patient, now in a different color to distinguish between the original marks and the actual treatment marks. All four fields are treated daily 5 days a week.

 

PORT FILM REVIEW

    A port film is obtained of all fields on the first treatment day to verify both the shape and the position of the field. Following approval of these films, weekly port films are taken of one lateral field and one anterior or posterior field alternating between these fields on a weekly basis so that over a two-week period, all fields have had a port film. If a misalignment is noted on any film, a correction is requested by the monitoring physician and the port film is repeated to verify the correction. In the retrospective review of port films to assess the effectiveness of the ALPHA CRADLE^® form described in this report, the port films taken following a requested field shift were excluded. It was felt that such films would not truly represent the ability to reproduce the set up over a period of several weeks since requested port films were taken any one day following the routine weekly film. It was also felt that the technologists would try extra hard to set up the fields correctly since they had been asked to repeat the port film. It is well recognized by many authors, that small differences between laser alignment systems, couches, etc. in CT, simulation, and treatment room may be present and give rise to misalignments observed on the first set of port films.^2,5-9 This problem was recognized in this port film review and the initial port films were therefore not included. The retrospective review of port films therefore included only the weekly routine port films.

    To assess the effectiveness of the prostate ALPHA CRADLE^® form described in this report, the routine weekly port films of 44 patients treated with the ALPHA CRADLE^® form were reviewed for misalignments observed by the monitoring physician during the treatment course. The findings were compared with that of 30 patients undergoing prostate irradiation without any immobilization device and without having a 3-D treatment plan. All patients in both groups were treated during the same period of time and whether they had an ALPHA CRADLE^® form and 3-D planning was the physician’s choice. Neither the technologists treating the patients nor the physicians evaluating the port films during the course of the treatment were aware that the port films would be reviewed later.

    The port film review of the immobilized patients included 213 routine isocenter set-ups while in the non-immobilized group there were 130 routine isocenter set-ups. When ort films of more than one field were taken on the same day, it was counted as only one isocenter set up since it represented the same set up.

 

RESULTS

    In the non-immobilized group of patients there was a misalignment rate of 23.1% versus 17.4% in the immobilized group. The most significant improvement in reproducibility when the immobilization device was used, was noted in the anterior – posterior direction where the misalignment rate was 12.6% without immobilization and 5.1 with the ALPHA CRADLE^® form. In the cephalad-caudal direction the misalignment rate was approximately 5% in both groups. In the right-left direction the misalignment rate was reduced from 18.0% without immobilization to 12.2% with immobilization.

    For both groups, approximately 75% of the misalignments were <5mm and 25% were <10mm. Only one requested isocenter shift was >10mm and this was a non-immobilized patient.

 

DISCUSSION

    The reason for the low number of errors in the cephalad-caudal direction is thought to be due to the fact that both anterior and lateral marks could be used when setting up the isocenter. In the right-left direction, the misalignment rate would likely have been lower with the ALPHA CRADLE^® form if the technologists had exclusively used the sagittal line on the ALPHA CRADLE^® form to set up the isocenter as instructed. The technologists have been setting up treatment fields to skin marks for many years and many of these patients had been treated before all of the technologists recognized that using the marks on the ALPHA CRADLE^® form lead to better reproducibility.

    Reproducibility of treatment field placement is fundamental to successful radiation therapy, but in treatment of prostate malignancies, reducing inadvertent irradiation of bladder and rectum may reduce acute and chronic injuries to these organs. The ability to reproduce the set up of prostate treatment fields accurately is critical, particularly when dose escalation is contemplated.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alpha Cradle^® Brand Immobilization Reduces Positioning Errors in Prostate Cancer Patients Treated with Six-Field Conformal Radiation Therapy

 

Seth A. Rosenthal, MD

University of California

Sacramento, California

(cover page)

 

ALPHA CRADLE^® BRAND IMMOBILIZATION REDUCES POSITIONING ERRORS IN PROSTATE CANCER PATIENTS TREATED WITH SIX-FIELD CONFORMAL RADIATION THERAPY

Seth A. Rosenthal, MD

University of California

Sacramento, California

 

INTRODUCTION

    Cancer of the prostate is the most common malignancy in American males (excluding skin cancers), with an estimated 132,000 cases diagnosed in 1992.² Of these patients, a significant percentage will present with localized disease amenable to potentially curative therapy with the local treatment modalities of radiation therapy (RT) and/or surgery. As physicians choose which therapeutic modalities to recommend for their patients, they must consider the probability of tumor control as well as the potential for morbidity that each therapeutic option may entail.

    The use of the dimensional conformal radiation therapy (3D-CRT) for patients with prostate cancer has been developed in recent years. 3D-CRT techniques enable the design of isodose surfaces which accurately conform to the target volume. This allows for reduction in the dose delivered to adjacent normal structures, permitting trials of dose-escalation to be initiated. ^3,9,10 In addition, the use of 3D-CRT has been show to result in a reduction in acute morbidity associated with RT for prostate cancer,^6,11 although longer-term follow-up will be necessary in order to determine if late effects will also be diminished.

    At present, a six-field coplanar conformal technique, similar to that described by Ten Haken et al¹⁵ is being used in our department for the entire treatment course or as a boost following treatment of the pelvic lymph nodes. As target volumes include not only tumor volume, but also a margin of error for variability in patient positioning, we set about to determine the variability that occurs in patient positioning during 3D-CRT, both with and without immobilization, in order to ascertain the amount of variability to be expected during RT, and to determine if the routine use of immobilization reduced variability in patient positioning.

    Inability to deliver the prescribed dose of RT to the tumor volume has resulted in reduced cure rates,⁵ and the uncertainty created by variability in patient positioning has been identified as a factor contributing to the overall spatial uncertainty.¹³ Immobilization devices may be useful in reducing the degree of spatial uncertainty secondary to positioning error. The use of immobilization may be especially important in the pelvis, where treatment to treatment variations may be larger than in other body sites. In a study examining variability in patient positioning for a variety of anatomic sites, a group from the Massachusetts General Hospital noted that 20% of the pelvic portals had positioning errors of > 1.19cm. This was higher than for any other body site studied.⁷ The relatively large uncertainties in pelvic positioning, perhaps not clinically significant when large pelvic fields were treated, are not appropriate for the treatment of prostatic carcinoma using tight margins and 3D-CRT.

    Conformal techniques are inherently vulnerable to uncertainties in patient positioning. They are dependent on accurate definition of, and tight blocking around, the target volume so that a minimum of normal tissue will be irradiated to high dose. As part of a continued program to develop conformal radiation therapy for prostatic carcinoma, we undertook a study to determine the magnitude of patient positioning errors associated with six field conformal therapy for carcinoma of the prostate, and to assess the impact of ALPHA CRADLE^® immobilization on these errors.

 

MATERIALS AND METHODS

    The study was conducted at two of the treatment facilities within the Department of Radiation Oncology at the University of California, San Francisco (UCSF): the facility at UCSF and the facility at the University of California, Davis (UCD). From August 1991 to February 1992, 22 patients were treated using CT planned six field conformal therapy for carcinoma of the prostate, either for the entire course of treatment or as a boost following pelvic irradiation. At one facility (UCD), patients were routinely treated with immobilization, while at the other (UCSF) no rigid immobilization was employed. Ten patients were treated with immobilization, and 12 were treated without immobilization. ALPHA CRADLE^® (Smithers Medical Products, North Canton, OH) Patient Repositioning Systems, similar to those described by Soffen et al,¹² were used to immobilize patients at UCD, with patients undergoing simulation and treatment planning CT, as well as daily treatments, in their immobilization devices.

    A total of 288 films were reviewed from the records of the 22 patients studied. For each film, bony landmarks were used as reference points, and a measurement of the deviation of the treated field from the simulated field (simulation-to-treatment variability) was made in both the Superior-Inferior (SI) and Anterior-Posterior (AP) Dimensions. Magnification effects were taken into account. For each portal, the AP and SI deviations were then calculated. This resulted in a single measurement which represented the deviation of the isocenter of the portal film from the isocenter of the simulation film, as shown in Equation 1:

 

Isocenter Deviation + [(AP Deviation)² + (SI Deviation)²]^1/2

 

The isocenter deviation values were sorted by magnitude and grouped by percentile. Average and median values were obtained for the cohorts of immobilized and non-immobilized patients. Statistical comparisons were obtained using the SAS software package.

    The treatment-to-treatment variability, that is, the deviation of each film from the average portal film position for an individual patient, was also determined. For each patient, the average SI and AP deviation of each film from the average deviation for each patient was then determined. The differences between these two measures of variability have been discussed previously,⁸ with the simulation-to-treatment variability representing the deviation of each film from the simulation film, and the treatment-to-treatment variability representing the deviation of the individual portals from the average deviation noted for that patient.

 

RESULTS

    A total of 288 portals were reviewed for 22 patients; 10 patients treated with immobilization, and 12 patients treated without immobilization. The average AP portal deviations were 0.3 cm for the immobilized patients, and 0.4 cm for those not immobilized. The corresponding deviations in the SI dimensions were 0.2 cm and 0.4 cm, respectively. There was no significant difference noted between the oblique fields and the lateral fields with respect to AP, SI, or isocenter deviation. The above values translated into an average difference of the isocenter from simulation-to-treatment of 0.4 cm for the immobilized patients, and 0.6 cm for those not immobilized, as shown in Table 1.

 

Table 1

 

(diagram)

 

The distribution of deviation from simulation was grouped into 0.25 cm intervals, and this data is presented in Table 2. For both the immobilized and non-immobilized cohorts, approximately one-quarter of the values were less than 0.25 cm. However, when the number of values less than 0.5, 0.75. and 1.0 cm were compared significant differences were noted with immobilization. 66% of immobilized values were <0.5 cm compared with 43% of the non-immobilized values. 98% of the immobilized portals were within 1.0 cm of the simulated isocenter, compared with 85% of the non-immobilized values.

 

Table 2

 

(diagram)

 

    The percentile distribution of simulation-to-treatment variability is presented in Table 3. There is a 0.2 cm difference in variability between the immobilized and non-immobilized cohorts at the 50^th percentile. A smaller difference noted at the 10^th and 25^th percentiles, and a greater difference for the 75^th and 90^th percentiles. If the 75^th percentile is examined, there is a 0.3 cm difference noted with immobilization, and at the 90^th percentile, a 0.4 cm difference. The increasing difference in variability without immobilization is demonstrated in Figure 1.

 

Table 3

 

(diagram)

 

(diagram)

 

Fig. 1

 

    The treatment-to-treatment variability for the films of each patient was also determined (Table 4). For the immobilized patients, the average variability was 0.4 cm, while for the non-immobilized patients it was 0.6 cm. Furthermore, there was a significantly larger number of non-immobilized patients noted with treatment-to-treatment variability of greater than 0.5 cm (p=0.01). These results indicate that those patients treated with immobilization had significantly less variation from their average treatment position.

 

DISCUSSION

    The impact of ALPHA CRADLE^® immobilization on positioning error in prostatic carcinoma has previously been examined in patients treated using a conformal, four-field technique. Soffen et al noted an average unidimensional (SP or SI) error of 0.33 cm, which translates to an average deviation of the isocenter of 0.47 cm in those patients who were immobilized.¹² These results are comparable to our findings of an average 0.4 cm deviation from simulation in those patients who were immobilized. The consistency of these results indicates that average errors in positioning of less than 0.5 cm from simulation can be expected in patients with prostate cancer if ALPHA CRADLE^® immobilization is used.

 

Table 4

(diagram)

 

    In addition to reduction in simulation-to-treatment variability, the treatment-to-treatment variability was significantly reduced for those patients who were immobilized. Only 1/10 of the immobilized patients had variability of more than 0.5 cm from average position, compared with 8/12 of the non-immobilized patients (p=0.01). This indicates that once a satisfactory position has been achieved for immobilized patients, the radiation oncologist can be assured that comparable set ups will be achieved throughout the course of treatment.

    The decrease in variability with patient positioning, although only 0.2 cm at the median value, is higher if one compares the 75^th or 90^th percentile values. This effect of immobilization in reducing larger magnitude errors more than smaller magnitude errors has been previously noted¹² and has important implications. In choosing a margin to the tumor volume to account for uncertainties in patient positioning, the radiation oncologist may select a margin which would encompass the tumor volume despite positioning uncertainties, in the vast majority of cases, rather than a smaller margin which would include the entire volume only 50% of the time. Thus it may be at least as important to consider the reduction in variability in positioning at the 75^th or 90^th percentile as at the median value, and the decrease in variability with immobilization is most apparent when these levels are compared. The use of immobilization significantly reduced the proportion of higher magnitude positioning errors, especially those greater than 0.5 cm. Over 90% of the immobilized patients had set up errors of <0.75 cm, compared with only 68% of those not immobilized. Optimal selection of tumor margin may make possible reductions in treatment volume which may spare both acute and long term toxicity and allow for dose escalation.

    An issue not addressed by this study is potential in vivo movement of the prostate relative to the bladder and rectum. Ten Haken et al noted an average difference in prostate position of 0.5cm relative to the full of empty status of bladder and rectum. This potential for in vivo mobility of target structures, along with variability in patient positioning, represents a potential limitation to the application of 3D-CRT techniques, and should be considered when designing target volumes. We are currently considering approaches to reduce the effect of this in vivo organ movement on tumor position, such as making efforts to consistently plan, simulate, and treat patient with bladder full and rectum empty. However, these are preliminary efforts, and further study of these factors will be important at 3D-CRT for prostate cancer continues to be refined.

    Reduction in acute morbidity has been noted in prostate cancer patients treated with conformal techniques as compared to non-conformal techniques. Soffen, Hanks, et al noted that when patients who were treated to small fields with conformal techniques were compared to historical controls treated with non-conformal techniques, a significant reduction in the number of patients noting urinary or rectal symptoms requiring medication and/or unplanned treatment breaks was noted. This reduction in acute symptomatology was attributed to an average reduction of 14% in the volume of both bladder and rectum treated using conformal techniques and immobilization when compared to stage matched controls.¹¹ Similar reduction in acute morbidity have been noted by Leibel et al.⁶

    The reduction in treatment volume associated with conformal therapy may also allow for dose escalation. Early experience from the University of Michigan suggests that toxicity can be maintained at acceptable levels with escalation of doses beyond 70 Gy if conformal techniques are used.¹⁰ This may be clinically significant for patients with Stage C disease, where there is a suggestion of dose response relationships for local control above 70 Gy.⁴ Caution will need to be used in trials of dose escalation, as there is potential for unexpected sever late effects. In a cohort of patients who received a proton beam boost to doses of 75.6 cobalt-Gy-equivalent (CGE), severe rectal injury was noted in 34% of patients, with the likelihood of rectal injury correlating with treatment of >40% of the anterior rectal wall.¹ This experience underscores the need to minimize treatment volumes if trials of dose escalation are to be successful.

    To illustrate the implication of decreased variability in patient positioning, we examined the consequences of changing the margin added to the prostate volume in order to obtain a target volume for a representative patient with a Stage T2a (B1) prostate cancer (Table 5). Using the Scandiplan treatment planning system, we found that if a 1.5 cm margin was chosen, a target volume of 214 cc resulted, but that if a 1.3 cm or 1.1 cm margin around the prostate can have on the final target volume, and in a corresponding fashion, on the volume of adjacent normal tissue treated. Although the absolute reductions in positioning error with immobilization may seem small in magnitude, they translate into potentially large differences in volumes of normal tissue irradiated. As noted above, small increases in the volume of anterior rectal wall treated may result in significant added morbidity.

 

Table 5

(diagram)

 

    Many factors must be considered when arriving at a target volume from a tumor volume. These include difficulties in the definition of tumor volume, potential microscopic tumor extension, type of beam arrangement used in the treatment plan, adjustment for build up of isodose lines near field edges, possible in vivo organ mobility, and variability in patient positioning. Recognizing that reduction of the variability in patient positioning corrects for only one of these factors, we have instituted the use of immobilization for all prostate patients treated using 3D-CRT in our department. However, if 3D-CRT is to achieve its full potential, all factors contributing to the spatial uncertainty in dose delivery will also need to be optimized. 

    The use of the ALPHA CRADLE^® immobilization devices has been incorporated into our routine treatment for patients with prostate cancer. The device is made at the time of initial, pre-CT simulation. Manufacture of the
ALPHA CRADLE^® form takes approximately 15 minutes. The patient then undergoes a CT scan for treatment planning (in some cases for diagnostic purposes as well) in the cast, and a verification simulation once the treatment plan has been generated. The use of immobilization devices has been well accepted by both patients and staff and has not presented any significant problems in our practice.

    Perceived difficulty in evaluating oblique portal films has been mentioned as a reason not to use 3D-CRT techniques. However, we have found that verification of the oblique fields used in the six field technique was not difficult once initial experience was obtained in reviewing simulation and portal films. The finding that there was no significant difference between the oblique and lateral films with respect to positioning error confirms our clinical impression that interpretation of the oblique films used in this six-field conformal 3D-CRT technique is not more difficult than the interpretation of portals obtained on conventional fields, and should not represent a limitation to the applicability of the six-field technique.

    The use of immobilization results in reduced simulation-to-treatment variability and a significant reduction in the number of positioning errors greater than 0.5 cm. The decrease in variability in patient positioning noted with immobilization allows the clinician greater assurance that the improved isodose distributions obtained with 3D-CRT will treat the target volume on a daily basis. In addition the reduction in the number of higher magnitude positioning errors may allow for smaller target volumes by decreasing the margin which must be added to the tumor volume in order to account for variability in patient positioning. The use of immobilization devices can be an important, and easy to institute, component of a 3D-CRT program for patients with prostate cancer. Research will need to continue in this area, as well as into the other factors contributing to the uncertainty in radiation dose delivery to target structures, if 3D-CRT is to achieve its full potential for the treatment of prostate cancer. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Does the Use of Alpha Cradle^® Forms With Pelvic Irradiation Reduce Positioning Errors?

 

Laura W. Jones, BSRT, T, CMD

Deborah Fuller, RTT

John Devine, MD

Rhonda Jones, RTT

Kermit Quesinberry, RTT

Nancy Ramsey, RTT

Clint Wynn, MRT

South Georgia Medical Center

Valdosta, Georgia

(cover Page)

 

DOES THE USE OF ALPHA CRADLE^® FORMS WITH PELVIC IRRADIATION REDUCE POSITIONING ERRORS?

Laura W. Jones, BSRT, T, CMD

Deborah Fuller, RTT

John Devine, MD

Rhonda Jones, RTT

Kermit Quesinberry, RTT, Nancy Ramsey, RTT

Clint Wynn, MRT

South Georgia Medical Center

Valdosta, Georgia

 

INTRODUCTION

    Consistent positioning accuracy is an important factor in the delivery of quality radiation therapy treatments. Conventionally, 4-field. pelvic irradiation, for prostate cancer was delivered to the tumor and surrounding area to a total of 4500 cGy. The tumor was then boosted 2000-2400 cGy with a smaller 4-field. technique or 120° lateral arcs. In order to reduce complication, current trends replace the arc technique with a reduced 4-field. plan utilizing extremely small (8 x 8 cm) fields.¹ Concern arose regarding the reproducibility of these small fields especially when utilized to treat obese patients. Techniques to improve accuracy and reproducibility were considered.² The intent of this particular study was to answer the question, “Does the use of an ALPHA CRADLE^® brand Patient Repositioning System with pelvic irradiation reduce positioning errors?”

 

METHODS AND MATERIALS

    Port film accuracy data was collected for 44 consecutive patients undergoing 4-fd. Pelvic irradiation during the time period 1990-1991 when ALPHA CRADLE^®

Forms were not routinely used for pelvic immobilization. This data was compared with data from 44 consecutive patients receiving 4-fd. Pelvic irradiation during the time period 1992-1993 when ALPHA CRADLE^® brand Patient Repositioning System were routinely used for immobilization. This data was organized according to Table I. Each film was rated as follows:

1)    Good: needing no changes

2)    Minor: needing minimal change of field alignment

3)    Major: needing significant change such as a geographic miss of the tumor

4)    Technical Error: film suboptional due to incorrect exposure, processor jam, etc.

By dividing the data into these categories, repeats caused by positioning errors could be isolated from the total number of repeated port films.

 

Table 1

(diagram)

 

    The ALPHA CRADLE^® forms were fabricated during the simulation process and used throughout the patient’s entire course of treatment. Although Smithers Medical Products, Inc. does have a pelvic form available, all the ALPHA CRADLE^® forms in this study were made using the revised ALPHA CRADLE^® MOLD MAKER II (Fig. 1) and ACMM FOAMING AGENTS.³

 

(diagram)

 

Fig. 1 Alpha Cradle^® Mold Maker II

 

    In order to make these custom ALPHA CRADLE^® forms structurally stable, a 10” x 10” x 1” piece of Styrofoam^® was placed inside the polyfoam bag in the weight-bearing area of cradle. After the chemicals were poured and patient positioned, a piece of 3” x 3” x 3” Styrofoam^® was placed between the legs to facilitate the foaming agent to form around each leg separately. When the ALPHA CRADLE^® form was completed (Fig. 2) the MOLD MAKER II was removed and the simulation continued. After fields were localized, the central ray (CR) extensions or laser lines were drawn on the patient and the ALPHA CRADLE^® form. If the CR itself fell on the form, the form was trimmed down so the CR fell on the patient’s skin.

 

(diagram)

 

Fig. 2 Pelvis Alpha Cradle^®

 

    When the patient was positioned in the treatment room, the table was raised to comply with a pre-determined tabletop to lateral CR measurement, the form was aligned with lasers, and patient was aligned with ALPHA CRADLE^® form and lasers. All measurements were verified and recorded and initial port films were approved. Port films were taken on all fields weekly for the remaining course of treatment.

 

DICUSSION / CONCLUSION

    The collected port film data was organized into the format of Table II. With the addition of ALPHA CRADLE^® brand Patient Repositioning System, repeat ports due to minor positioning errors decreased from 12.8% to 9.6%. Statistically overall, this represented a 25% decrease in minor positioning errors (12.8 – 9.6%. Statistically overall, this represented a 25% decrease in minor positioning errors (12.8 – 9.6 / 12.8 x 100 = 25%).

    This data was collected over a two year time period during which there were several staff change-overs. Once a stable staff was in place the technique errors dropped dramatically. There were no major position errors noted for any of the set ups.  

     Since all parameters (with the exception of ALPHA CRADLE^® form use and personnel change) remained the same, the use of ALPHA CRADLE^® forms was determined to be a major factor in the 25% decrease in minor positioning errors. The study showed that the use of ALPHA CRADLE^® forms for immobilization during 4-fd. pelvic irradiation is a valuable tool for positioning reproducibility.

 

Table 2

 

Port Film Analysis

(diagram)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Technical Aspects in the Use of Belly Boards for Small Bowel Minimization

 

Lori E. Frank, RTTR, CMD

Laura A. Rowley, RTTR, CMD

Thomas G. Shanahan, MD

Minesh P. Mehta, MD

University of Wisconsin Hospital and Clinics

Madison, Wisconsin

(cover page)

 

TECHNICAL ASPECTS IN THE USE OF BELLY BOARDS FOR SMALL BOWEL MINIMIZATION

Lori E. Frank, RTTR, CMD

Laura A. Rowley, RTTR, CMD

Thomas G. Shanahan, MD

Minesh P. Mehta, MD

Univ. of Wisconsin Hospital & Clinics

Madison, Wisconsin

 

    Many factors have been shown to affect the tolerance of the small bowel to external irradiation. Some examples are previous surgery, pelvic inflammatory disease, diabetes mellitus, hypertension, age, and the radiation variables of time, dose, and fractionation^1,2,3,5,7,8. The occurrence of late complications may vary 2-30% in the first 18 months of follow-up because of the numerous factors affecting long term complications.

    Both acute and late gastrointestinal side effects correlate with the volume of small bowel receiving 45 Gy or more with conventional treatment setups and fractionation; however, the exact extent of the relationship between volume treated and small bowel tolerance has not been determined^1,4,6,7,9.

    The original purpose of this study was to attempt to reduce the volume of small bowel within the radiation portals during treatment of the pelvis or abdomen. We incorporated the use of a unique technique that allows the maximal

displacement of the small bowel from the area of treatment using a custom made “BELLY BOARD” (Fig. 1).

 

(diagram)

 

Fig. 1 Sagittal CT showing anterior and superior abdomen displacement with patient in the Belly Board.   

 

METHODS AND MATERIALS

 

PATIENT SELECTION

    Thirty patients under treatment for cervical, endometrial, rectal, prostatic or bladder malignancies were studied. Seventeen patients had undergone prior pelvic surgery. Patient age ranged from 34 to 83 years and weight ranged from 110 to 260 pounds. All patients were treated to doses of 45 to 51 Gy using conventional daily fractions of 1,7 to 2.0 Gy. Some patients received another 5 to 20 Gy boost volume effectively shielding the small bowel. Patients must be able to support their own weight with their arms to make the use of a BELLY BOARD feasible.

 

CONSTRUCTION

    For the study, all patients were evaluated with treatment planning CT in supine and prone positions. The patients were given both verbal and written instructions to enable reproducible bladder distension.² Patients received one liter of oral contrast 45 minutes before the scan. Anterior or posterior and lateral scanograms were obtained. CT cuts of one CM thickness were obtained for the entire length of the treatment area. Prior to the prone scan, the custom BELLY BOARD was fabricated.

    Two or three Styrofoam^® boards measuring 40 cm wide by 60 cm long by 2.5 cm thick were inserted into a large, strong plastic bag. Polyurethane mold material was mixed and added into the bag on top of the Styrofoam^® sheets. The mixture was allowed to breathe adequately (approximately 45 seconds) and then the bag was securely sealed. The patient then lies on top of the bag and the mold mixture grows around the body and forms to the contours of the patient. Once the mold has hardened sufficiently (5 minutes), the patient’s xiphoid process and the superior border of the planned pelvic treatment field were identified clinically or by scanogram or fluoroscopy and these margins were marked on the patient and on the mold to assure accurate repositioning. After removing the patient from the mold, a hole was cut at the previously designated margins, leaving the lateral edges of the mold intact for increased stability (especially important for obese patients). The extracted hole usually measures 25 x 30 x 5-7.5 cm deep. All rough and exposed edges were taped for patient comfort. The patient then returned to the mold in the original position using the alignment match lines, and prone CT scan completed.

    Oral contrast as described above was used for simulation of a conventional four field technique incorporating cerrobend blocking were indicated both with the patient supine and prone. The BELLY BOARD mold was used for the simulation in the prone position.

 

PLANNING AND DOSE VOLUME ANALYSIS

    An in house image processing package was used to determine the actual volume of small bowel within the treatment areas for both supine and prone positions. The physician outlined the small bowel regions on each CT cut. Treatment fields with isodose lines incorporated were digitized from treatment plans and correlated with the CT images. All areas of small bowel within the 45 Gy isodose line were highlighted (Fig. 2). The areas were summed on each slice and the total volume of small bowel was computed by multiplying the total area by the individual slice thickness. When using the BELLY BOARD in the prone position, it was found that the volume of small bowel displacement increased by 66% as compared to the usual supine position. Bladder distention to S1/S2 was also routinely achieved. No patient had an increase of small bowel volume irradiated when using the BELLY BOARD.

 

(diagram)

 

Fig. 2 CT scan slice showing position of 45 GY isodose curve over outlined small bowel in prone Belly Board position.

 

VARIATIONS

    A custom mold was also fabricated for abdominal malignancies following the same basic steps as with the BELLY BOARD. An extra 20 x 20 cm Styrofoam^® piece was placed on top of the larger Styrofoam^® sheets, on the affected side in the area of the planned radiation portal. The hole was cut to midline only from the unaffected side. This allows the small bowel to drop laterally away from the treatment field.

 

CONCLUSION

    The use of a prone BELLY BOARD technique for pelvic as well as for upper abdominal malignancies, displaces, and thereby spares, as considerable amount of small bowel which reduces the gastrointestinal complications and patient discomfort. The manufacture of each custom board is a quick and simple process. The materials necessary to construct each board are easy to obtain and relatively inexpensive. The board can be formed to any shape necessary to spare the bowel or other internal structure for pelvic as well as for abdominal treatment portals. The board I fairly comfortable for the patient and increases the stability and reproducibility of treatment fields. Storage presents few problems and each mold is disposed with institutional refuse. We have investigated the attenuation factors and effects on skin sparing for various energies above 10 Mv, as previously studies.¹⁰

    The ultimate goal of this project was to reduce morbidity sufficiently to allow an increase in total dose when clinically necessary. By using the prone BELLY BOARD technique, the small bowel no longer remains a dose limitation factor.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER FIVE

 

 

REPOSITIONING AND IMMOBILIZING THE CNS AXIS

(cover page)

 

ALPHA CRADLE^® PATIENT REPOSITIONING SYSTEMS:

CNS, CNS-P

    Smithers Medical Products, Inc. is proud to introduce the first truly prone customized repositioning form using a polystyrene shell and polyurethane foaming agent. This new form, available in adult and pediatric sizes, immobilizes the patient from the top of their head to the base of the hips. Our unique patented design allows foam to form around the patient’s head, while allowing ample breathing space. Foam fills the supports around the patient’s forehead, zygomatic bone and base of the mandible. This unit is connected to the larger base that continues the flow of foam from the patient’s neck to the ilium. This form is the first of its kind to offer immobilization of the entire cerebrospinal axis, all in less than 20 minutes fabrication time.

    It is imperative that constant attention be given throughout the foaming process to the patient’s face. Although to date no leaks have been reported, a leak could cause a great deal of anxiety to the patient. If you notice a leak, immediately remove the patient from the form and begin the process again with a new form. Defective forms are replaced immediately free of charge.

    Remember that the head may tend to lift out of the form. If this happens, wait until the foam feels spongy and then carefully press the back of the patient’s head deep into the foam. This should prevent the head from rising again. It is imperative with this form that the patient is centered correctly inside the form. Using your sagittal lasers, make sure the patient remains centered correctly. Keep the arms pressed deep into the foam for a good impression.

 

ACMMII

    By placing the top end of the bag at the patient’s lower lip, the bag can be pulled up along the mandible to the tip of the zygomatic arch, back to the patient’s ear. By immobilizing the mandible in this fashion, movement of the patient’s head is reduced considerably. Before making the form, measure the height of the patient’s nose, from their chest, when laying supine. By placing a support piece of polystyrene inside of the bag that corresponds to this height, you will allow the base of the skull to drop to the same plane as the vertebrae.

   

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Use of Alpha Cradle^® Foam and Plaster Bandage In the Positioning of Patients For Cranio-Spinal Irradiation

 

Mary Z. Hare, BS, RTT

Rosemary T. Reed, BS, RTT

S.U.N.Y. Health Science Center at Syracuse

Syracuse, New York

(cover page)

 

THE USE OF APLHA CRADLE^® FOAM AND PLASTER BANDAGE IN THE POSITIONING OF PATIENTS FOR CRANIO-SPINAL IRRADIATION

Mary Z. Hare, BS, RTT

Rosemary T. Reed, BS, RTT

S.U.N.Y. Health Science Center at Syracuse

Syracuse, New York

 

 

INTRODUCTION

    In the field of radiation oncology, there is a constant search for efficient and cost effective methods of attaining precise and reproducible radiation treatments. This becomes especially important when treating the cranio-spinal axis. The necessity for accurate matching of the gaps and/or junctions of the various treatment portals are well understood. A well recognized fact is the importance of patient positioning in order to achieve these goals.

    In the past, the plaster bandage cast has played a large role in the positioning of patients who require this method of treatment. This role is presently changing with the increased use of other materials such as the vacuum former and the thermoplastics. The thermoplastics are relatively fast and the vacuum former is a slow process; however, both require elaborate equipment and a great deal of work space. In both methods, ultimately, a hard plastic is formed in the desired shape of the patient.

 

MATERIALS AND METHOD

    It is important to have all the necessary materials prepared ahead of time. This allows for maximum efficiency in the time requirement on behalf of the patient as well as the staff. The initial materials are the usual materials which are needed when making a plaster cast. These include a table for the patient to lie on, strips of plaster bandage pre-cut to the various desired lengths, warm water for the plaster, a bathing or shower cap for the patient’s hair and a body stocking net to place between the patient’s skin and the plaster bandage. Once the cast is complete, the second phase may proceed. Along with the ALPHA CRADLE^® brand foaming agents (Fig. 1), the recommended materials include the ALPHA CRADLE^® MOLD MAKER board with its dividers, a second board of similar size and thickness, a plastic bag in which to pour the chemicals, four stilts which have the dimensions of 2” x 4” x 8” (this is approximate number since the height will depend on the size of the patient), and a pair of latex gloves.

 

(diagram)

 

Fig. 1 One set AC325 foaming agents and polyform bag.

 

    Once all the materials are prepared and the patient has arrived, prepare the patient by having them undress and lie down in the supine position. Place a single layer of stockingnet over them from the chin down to the mid thigh. Straighten the patient as well as possible, making sure the head is straight, the chin is extended, and the shoulders are pulled down toward the feet. Begin placing the wet plaster strips lengthwise along the patient, paying attention to coverage of the chin, shoulders and arms. Allow the plaster to fall onto the flat table top to form a flange. This flange is useful later because it ensures that the cast is flat and level. Begin the next layer by placing the plaster long the width of the patient’s body, paying special attention to the neck, chin and thighs. It is helpful to reinforce the inferior edge to keep the plaster from breaking due to the pressure caused by the patient’s lying down and arising from treatment. Next, thin strips of plaster are necessary to form the forehead, nose and cheek supports. It is helpful to frame the cheeks and forehead with the plaster allowing the strips to extend down onto the chest. By alternating the forehead/cheek strips with the nose strips and working with the plaster, a seal is formed which will hold its shape throughout the entire treatment. Once these are in place, it is necessary to place more horizontal strips across the chest, chin and shoulders, again working with the plaster to ensure that the plaster does not separate. Diagonal plaster strips are now placed across the chest, abdomen and hips forming “X” patterns. The term “knobs” best describes the next step. Four knobs are formed by bunching a plaster strip and allowing the ends to extend over the cast. These four knobs are strategically placed, two in the chest region and two in the pelvis region. These form protuberances which help to anchor the cast into the ALPHA CRADLE^® form. Single strips of plaster are now placed over the exposed ends in order to secure the knobs into place. At this point in time it is helpful to continuously rub the plaster, this blends it and enables it to become a single unit. This prevents the individual sheets of plaster from separating and splintering. All this must be accomplished quickly because if the plaster is allowed to dry, it becomes difficult for the sheets to adhere to each other. It is important to remember that enough plaster is necessary to form a stable shell which can be lifted off the patient without any flection, but not so much as is usually needed to provide total support of the patient’s weight. It is also felt to be necessary to extend the cast almost to the patient’s knees in order to provide ample support of the legs which prevents the patient from “jack-knifing” in the cast which can be created by the weight of the lower leg not having the proper support. Before proceeding, the cast must be thoroughly dry. The drying time will vary from two to four days depending on the condition of humidity.

    In preparing the materials for the second phase it is imperative to decide how much of the ALPHA CRADLE^® brand foaming agents are necessary. An important consideration is the size of the patient. For children, two sets may be all that are needed; however, for adults, as many as four sets may be necessary.

    Begin by laying the cast, in the supine position on top of the ALPHA CRADLE^® MOLD MAKER board (Fig. 2). Position the barriers along the sides and ends of the casts to provide a dam and form the sides of the ALPHA CRADLE^® form. Open the plastic bag and lay it over the cast (Fig. 3).

 

(diagram)

 

Fig. 2 Plaster cast on ACMMII with barriers in place.

 

(diagram)

 

Fig. 3 Polyform bag in place.

 

Wearing the gloves from this point on helps to protect the skin in case any spillage occurs. Shake and combine Parts 1 and 2 as directed. Pour into the bag as recommended, evenly distributing the chemicals (Fig. 4).

 

(diagram)

 

Fig. 4 Carefully pour foam deep into bag.

 

Close the open end of the bag. While the chemicals begin to rise, carefully watch the foam and redirect it if it appears that too much is in one area. Stand the stilts outside of the barriers and place the second board on top of the stilts (Fig. 5).

 

(diagram)

 

Fig. 5 Board shown on top of barrier stilts.

 

Oftentimes weight needs to be applied in order to prevent the rising chemicals from lifting the board and to promote the desired flat surface. The flat surface is necessary for the apparatus to lie flat on the tabletop. The ALPHA CRADLE^® form must reach the board and flatten against it! Allow the ALPHA CRADLE^® form to harden, as directed. After hardening, remove the top board. What will be seen is the flat surface of the ALPHA CRADLE^® form. Lift the entire cast and inspect it for any areas which may be in the treatment portal more than desired. This occurs around the lower face and neck regions (Fig. 6). These areas will need to be trimmed. A simple keyhole saw is all that is necessary to trim the ALPHA CRADLE^® form and a cast cutter is helpful for the plaster.

 

(Diagram)

 

Fig. 6 Completed form – face & neck region shown.

 

    Lining the cast with a thin layer of rubber or foam or padding helps to make it a little more comfortable for the patient to lie in. If this is accomplished, the face is especially important, since the nose and chin seem to be the weight bearing areas for the face and becomes the most uncomfortable area.

    The last step is covering the cut edges with tape or any desired material to prevent scratching the patient during their daily entry and exit from the cast (Fig. 7).

 

(diagram)

 

Fig. 7 Completed form shown with edges taped over for comfort.

 

DISCUSSION

    The problem of leveling the cast, which traditionally was solved by wooden shims on 2” x 4”s with this process is now solved by using a table or even the floor as the leveling guide. The flanges on the sides of the cast provide the base which ensures that the cast is level and flat against the board. Next, the stilts, which are all equal in height, provide the factor which determines the desired height of the ALPHA CRADLE^® form. It is important to note that the nose is often the tallest structure, so the stilts need to be slightly taller than the nose. This allows for air to flow which helps make breathing easier (Fig. 8).

 

(diagram)

 

Fig. 8 This height allows patient to breathe easily during foaming process.

 

 

    By placing the barriers on the edge of the flanges it allows the ALPHA CRADLE^® form to mold by the arms. This provides a strong, stable support for the arms. This may seem to be unimportant while the patient is lying down because the arms are not very heavy; however, during entry and exit from the cast, the patient places his full weight in these areas in order to raise and lower himself. While this is of little importance if the patient is a small child who will be placed into position by a technologist, it is extremely important in an adult patient who will be positioning himself.

    The chin does not require as much material. Even a relatively thin layer of ALPHA CRADLE^® form provides ample support for the daily stress created in the simple act of placing the head into position. Because the chin, nose and forehead are nestled into their respective places, the daily discrepancies in positioning are minimal. Repeated port films of the brain portals have shown consistently reproducible positioning.

    The only additional piece of support which has been previously unmentioned, is a pillow or sponge which is to be placed under the ankles. This alleviates the stress placed on the leg caused by the weight of the leg. This stress can cause avoidable discomfort to the patient.

    In the event the cast becomes separated from its ALPHA CRADLE^® form base, the plaster “knobs” allow the cast to be placed into its base securely, snugly and without any doubt that it is positioned correctly.

 

CONCLUSION

    The described ALPHA CRADLE^® form provides an alternative to the problem of stabilization of the fabricated plaster bandage cast used in the cranio-spinal axis treatment technique. The ALPHA CRADLE^® form provides the cast with strength and durability. Because of the strong sides and flat surface, the cradle also provides the cast with stability and support which is unseen in the cast which employs plaster alone. Also, in the traditional plaster cast, so much plaster is necessary to give it enough strength that it soon becomes very heavy for the technologist to place and remove from the treatment couch. The feature of the ALPHA CRADLE^® foam inherently being lightweight causes the finished cast to weigh much less.

    All the described qualities make this an invaluable tool to assist in the consistent reproducibility which is necessary in the delivery of radiation treatments. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stabilization Device for Patients Undergoing Cranio-Spinal Irradiation

 

 

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

STABILIZATION DEVICE FOR PATIENTS UNDERGOING CRANIO-SPINAL IRRADIATION

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

 

 

 

INTRODUCTION

    Cranio-spinal irradiation  (CSI) is required in patients with medulloblastoma, and sometimes in patients with lymphoma and leukemia, usually as a preventive mode of therapy. Patients requiring CSI are usually children or young adults since these tumors most frequently occur in the relatively young population. The technique applied in the treatment of the CSI usually require that the patient is in the prone position while the brain and cervical spine is treated through opposed lateral fields and the spinal axis through one or two posterior fields.

    For most patients, the prone is less comfortable than supine and is therefore less likely to be maintained throughout a treatment session unless they are positioned in a body shell. Children often move unintentionally and if they are in an uncomfortable position the risk of movement is increased. Comfortable and effective immobilization techniques are therefore needed.

 

TREATMENT

    The most commonly used treatment technique for CSI consists of opposed lateral brain and cervical spine fields and one or two posterior spinal fields. To avoid beam overlap at the junction between the lateral and the posterior fields, the couch is turned such that the caudal margin of the lateral brain field traverse the neck perpendicular to the spin axis.

The collimator is turned until the caudal margin of the brain fields is parallel with the diverging posterior field margin. This field matching technique is similar to that frequently used when matching multiple breast treatment fields. The proximity of the lens of the eye to the radiation beam and the difficulties with matching of these field margins require an effective immobilization device.

    For nearly 15 years, customized half-body plaster casts have been made in our department for patients requiring CSI. These casts were relatively easy to make but required 2 days to dry before they became strong enough to support the patient’s weight. These casts, because they also included the arms, were often wider than the couch. To enter and exit the casts in the prone position, it was necessary for the patients to brace themselves with both arms on the cast. The pressure thus exerted on the cast was often more than the cast could tolerate. For many patients, particularly those with neurologic deficits, getting in and out of the cast was difficult. Another problem was the delay by 2 to 3 days in starting the treatments because the cast needed to dry before it was strong enough to support the patient’s weight. An increasing demand to begin treatment with short notice resulted in the development of an ALPHA CRADLE^® form for patients receiving CSI.

 

POSITIONING DEVICE

    The CSI ALPHA CRADLE^® consists of a Styrofoam^®* form which roughly fits the shape of the prone patient’s head and torso. The head form, which is attached to the body form, consists of four walls that are approximately 4” high (Fig. 1). These walls support the head and has an opening for the patient’s face. A 1.5 mil polyvinylchloride (PVC) sheet is taped to the edge of the four walls so that is forms a channel approximately 2” in diameter. The channel opens into the body form on each side of the head. The body form is enclosed in a PVC sheet to prevent any foam from touching the patient. The head support is placed so that the patient’s head is partially over the edge of the couch provide unobstructed view and air flow while the ALPHA CRADLE^® form is being made.

    Approximately 30 cc of foaming agents are poured into each opening of the channel and about 600 cc is poured into the body form before the patient lies down in the prone position. The patient’s head is resting on the channel where the foam has been poured. The foam swells up around the patient’s face leaving an opening

 

*Registered by Dow Chemical

(bottom of page)

for the eyes, nose and mouth. The PVC sheet covering the body part of the ALPHA CRADLE^® form is pulled up between the patient’s arms and the torso so that the foam can raise and form a mold of the arms as well as of the torso (Figs. 2A and 2B).

    When the foam has hardened, the patient lifts up the head and a softened thermoplastic sheet is placed across the head support. The patient then resumes the position and thermoplastic sheet is pressed up against the face to form a tight mask (Fig 2B). When the patient lies down, a visual check is made to see that the patient is straight and that the chin is raised so that the posterior spinal field will not exit through the oral cavity. In some patients it is necessary to elevate the torso so that the head and the torso are level. This can be accomplished by placing a large piece of Styrofoam^® in the body part of the ALPHA CRADLE^® form prior to pouring the foaming agents.

    During the simulation procedure, openings are made in the Styrofoam^® and the thermoplastic sheet so that the patient’s eyes can be visualized. Markers are placed on the lateral canthus of the eyes during the simulation procedure and a visual check is made to assure that the lens of the eye is out of the radiation field during each treatment set-up.

 

(diagram)

 

Fig. 1 A polyvinyl sheet is taped around the face support to form a channel around the head. The foam will expand inside the polyvinyl sheet and form a face support. A polyvinyl sheet is also taped over the torso portion of the Alpha Cradle^® form. Foaming agents poured into this section will expand and form a mold around the patient’s torso.

 

RESULTS

    The ALPHA CRADLE^® form, CNS, is fairly new and has successfully been used in only a few patients. One was and adult patient with hemiparalysis. He was able to get in and out of the ALPHA CRADLE^® form with very little help. It was felt by the technologists who treated the patient, that if he had been in a total body plaster cast, it would have required several people to help him get in and out of the cast. Review of port films of the patients treated in this ALPHA CRADLE^® brand CNS form indicated that the repositioning was excellent.

 

DISCUSSION

    Precise repositioning of patients in the prone position is quite difficult and for many patients it is also a difficult position to maintain. Patients requiring CSI often present with some neurological deficits that makes positioning even more difficult. Complex geometric matching of beam edges in the spinal cord and the proximity of critical organs requires precise repositioning of the patient for each treatment session. This CNS form has proven to be effective, easy to make, and comfortable for the patients.

 

(diagram)

 

Fig. 2A An impression of the arm position, made by pulling the polyvinyl sheet between the arms and the torso, aids in repositioning the arms.

 

(diagram)

 

Fig. 2B A thermosplastic sheet, softened in warm water and draped over the patient’s face, aids in repositioning the head.     

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Utilization of an Alpha Cradle^® Form For the Positioning of a Cranial Spinal Port

 

Jane V. Berby, RTRT

J. David Todd, RTRT

Indiana University Medical Center

Indianapolis, Indiana

(cover page)

 

THE UTILIZATION OF AN ALPHA CRADLE^® FORM FOR THE POSITIONING OF A CRANIAL SPINAL PORT

Jane V. Berby, RTRT

J. David Todd, RTRT

Indiana University Hospitals

Indianapolis, Indiana

 

    Treatment of the cranial spinal axis can create difficulties with the reliability and reproducibility of the treatment portals. Most patients are uncomfortable lying prone, which creates positioning problems. Many institutions utilize the prone pillow when patients are to be treated in the prone position. While the prone pillow has improved patient comfort, it has not been able to assure the therapist that the patient is in the exact treatment position. Because of this variable the Department of Radiation Oncology at Indiana University Medical Center has developed a customized immobilization device for the treatment of cranial spinal ports. We have found that this immobilization device increases the reproducibility of this treatment set up.

    Our customized prone immobilization device utilizes Smithers Medical Products, Inc. ALPHA CRADLE^® brand products, aquaplast and Styrofoam^®. Once the required products have been acquired a therapist can make this immobilization device in ten simple steps.

 

1) Prepare the ALPHA CRADLE^® foaming agents as directed by the manufacturer. Once mixed pour the foam into the provided bag (Fig. 1).

 

2) Next, spread the foaming agents evenly inside the bag. The foaming agents should be spread over an area large enough so that the ALPHA CRADLE^® form will extend from the patient’s shoulders to their hips. After the foaming agents are spread out fold the bag to the opened end so that the foaming agents are contained (Fig. 2).

 

3) At this point the patient is instructed to lie on the polyform bag in the prone position. Utilizing the slatted board and wood inserts the bag is formed around the patient. Special attention must be paid to mold the ALPHA CRADLE^® form around the patients shoulders and arms (Fig. 3).

 

(diagram)

 

Fig. 1 Carefully pour foam deep into bag.

 

(diagram)

 

Fig 2. End of bag is carefully folded.

 

(diagram)

 

Fig. 3 Keep the rising bag of foam tightly against the patient using the dividers.

 

4) After the ALPHA CRADLE^® form has hardened the patient is helped to a sitting position. The mold is then flipped upside down and double sided foam tape is placed on the ALPHA CRADLE^® form. The protective paper is then removed and the mold is turned back over and squarely placed on a large sheet of Styrofoam^® (3’ x 4’ x .5”) which serves as the base (Fig. 4).

 

5) The patient is then asked to lie back down in the mold and a piece of Styrofoam^® that is approximately 2”-3” high is positioned under the forehead for support. It is very important that the head be positioned in a neutral position with the face straight down. The position of the support piece is marked and it is then secured with double sided foam tape (Fig. 5)

 

6) Once the ALPHA CRADLE^® form and forehead support have been secured a final piece of Styrofoam^® is secured to the top of the main Styrofoam^® base. A warmed piece of Aquaplast^® is then placed on the edge of the ALPHA CRADLE^® form where the patient’s chest would be. The Aquaplast^® is then stretched across the forehead support and molded around the top piece of Styrofoam^® (Fig. 6).

 

7) The patient is then instructed to lie down; the head is positioned and the aquaplast is molded to the patient’s face. Once the aquaplast has hardened the patient can get up (Fig. 7).

 

8) To provide the immobilization device with greater stability, 2”-3” nails are pushed through the ALPHA CRADLE^® form and Styrofoam^® base. It is very important that the nails be of correct length so that the protruding points will not injure anyone (Fig. 8).

 

9) The last step we take in this process is to create greater patient comfort. To do this we place moleskin over the aquaplast where it meets the ALPHA CRADLE^® form, Additionally, we cut pieces of moleskin to place on pressure points in the mask. Most often the moleskin is put in the chin and forehead areas (Fig. 9).

 

10) The final product, a customized cranial spinal immobilization mold (Fig. 10).

 

(diagram)

 

Fig. 4 Double-sticky tape is placed on the back of the form.

 

(diagram)

 

Fig. 5 The form is mounted on a support piece.

 

(diagram)

 

Fig. 6 Aquaplast^® is molded around the patient’s face by placing it on the Styrofoam^® support pieces.

 

(diagram)

 

Fig. 7 Aquaplast^® has been molded to patient’s face.

 

(diagram)

 

Fig. 8 Nails must be placed carefully.

 

Fig. 9 Moleskin is placed on chin and forehead areas.

 

(diagram)

 

Fig. 10 Completed form.

 

 

    Increased immobilization is the main advantage of this ALPHA CRADLE^® form. Additionally, we have found three other advantages of this customized mold. First, it provides the patient with greater comfort while lying in the prone position. Secondly, we have found that the therapists are less apprehensive when positioning and treating patients with cranial spinal portals. Thirdly, many of the positioning marks can be placed on the mask and not the patient’s face.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Medulloblastoma Immobilization and Treatment Considerations

 

 

Edward J. Goldschmidt, Jr., Physics Technologist

Cooper Hospital

University Medical Center

Camden, New Jersey

(cover page)

 

MEDULLOBLASTOMA IMMOBILIZATION AND TREATMENT CONSIDERATIONS

 

Edward J. Goldschmidt, Jr.

Cooper Hospital/University Medical Center

Camden, New Jersey

 

MATERIALS NEEDED:

SMP ALPHA CRADLE^® brand Mold Maker [includes: slotted board, dividers, chemical set (bottles 1 and 2), plastic bag, protective head cap, protective gloves). Small piece of Styrofoam^® for head rest, additional board (12.5 ft. x 1-2 ft. wide x .5-1 inch thick) Spirit level, marker, masking tape, centimeter ruler, and lateral isoline lasers (for optional technique]

 

INTRODUCTION

    The plastic bag enclosed with the Smithers Medical Products, Inc. ALPHA CRADLE^® brand foaming agents must be tapered to accommodate variations in each patients anatomy. The following modified fabrication procedure will suggest approximate measurements. They are included as a benchmark reference only and it should be understood that inherent latitude exists. The latitude is given because of expected differences in patient cooperation and body size.

    Since most medulloblastoma patients are children, it becomes advantageous to have more than one person available at the time of the form fabrication and adjustment. Where additional healthcare personnel problems exists, ancillary medical or civilian personnel can be utilized to guarantee the child’s peace of mind. Having the child’s parent or guardian present during form fitting can in most cases expedite the fabrication process without incident. Ancillary personnel will be required only for the form assemble process and will be asked to leave just prior to the simulation procedure. The fabrication guidelines suggested below are easy to follow, accomplish, and show marked reproducibility if done carefully. However, we strongly suggest that any institution wishing to use this procedure first carry out a practice modified ALPHA CRADLE^® form on its own before attempting on actual patient.

 

FABRICATION PROCEDURE

Part One – Tapering the plastic bag for individual patient size.

    The intent of tapering the supplied bag is to distribute the SMP ALPHA CRADLE^®* form’s foaming agents, to achieve uniform form thickness. Optimum immobilization is achieved through the SMP system when the supplied foaming agents are distributed over a minimally defined surface area. This creates a sturdy immobilization shell which will easily endure through out an entire course of radiotherapy treatments which is typically three to five weeks. 

 

*Registered by Smithers Medical Products, Inc.

(bottom of page)

 

   Step 1 – To determine the required length of the form bag, have the patient stand erect with neck flexed such that his/her chin can rest in the suprasternal notch area. Next, remove the plastic bag from the ALPHA CRADLE^® kit and hold the edge of the open end such that it extends two centimeters superior to the patients lower lip. Hold the edge in place with one hand, and let the bag hang down touching the anterior surface of the patient. Then mark (use marker pen) a small line on the bag at the level of the iliac crest of the pelvis.

    Step 2 – To determine necessary bag width, keep the patient in the erect position and carefully wrap the bag around the front of the patient. Be sure the sides of the bags are symmetric with respect to the spinous processes (i.e. sides of bag will touch patients back). Hold bag in place with one hand and with the other palpate the medial edge of the scapula. Mark an additional line corresponding to the medial edge of the scapula. Repeat process for other scapula.

    Step 3 – Now fold the sides of the plastic bag to the lines that were just made and tape the folded portion with masking tape lengthwise. The resulting taped creases will now serve as the width of the bag. Next, fold the bottom of the bag to its corresponding marked line and tape the folded portion crosswise. This taped crease will serve as the bottom of the cradle bag. 

 

   Step 4 – Place the slotted ALPHA CRADLE^® MOLD MAKER on the simulation table lengthwise. The additional board (see materials needed) is placed on top of the slotted board at a midplane patient position. The protective head cap should now be placed on the patient’s head. This will prevent any accidental contact of the foam with the patient’s hair. The supplied gloves should be placed on the fabricators hands before attempting use of the foaming agents, as this will afford the fabricator maximum skin protection. Note that it is imperative that the following steps be performed in an expeditious manner so that the foaming agents do no harden before required. The SMP ALPHA CRADLE^® MOLD MAKER kit is equipped with a set of divider boards that fit within the large slotted board. They should be in close proximity to the simulation table at this time.

    Step 5 – The SMP ALPHA CRADLE^®* MOLD MAKER instruction sheet included with the fabrication kit should be previously read and shall now be readily available during the procedure for reference. During the form construction process, steps 1 through 7 (on sheet) should be done at this time, omitting step 3 (on sheet) as it has already been accomplished (see attached sheet).

    Step 6 – After the foam has been poured into the bag, the open end of the bag will be folded over slightly. This creates a crease which must be taped to prevent bag leakage. Next, the additional board is lifted up being careful to keep it as level as possible. This will prevent any uneven rise of the foam. Place it on a previously determined level surface near the simulator table.

    Step 7 – With the patient sitting on the end of the slotted board with his/her buttocks completely on the board, have the patient lie back on the board. Place folded sheets underneath the patients occipital region, this will compensate for the patients chin flexion into his/her suprasternal notch. The folded sheets should be adjusted to proved adequate support under the occipital region. The patient’s arms should be straight down at their sides with palms touching the lateral pelvis. The entire spine as well as the patients legs must be straight before attempting to place bag in position. With the patient correctly positioned, the additional board is lifted directly above the patients chest. Next, it is turned over placing the bag on the patients chest, here you will notice a non-uniform distribution of foaming agents in the region of the shoulders and neck. Also, there will be a tendency for these regions to become thicker then the others, but, this you will see is advantageous for the patients immobilization.

    Step 8 – Lift the superior end of the bag so that the edge of the bag is at the level of the lower lip. Adjust the bag side to side until the bag is symmetric to the patients width. Make sure the patients chin is resting in the suprasternal notch area, and superior edge of the bag should be at the lower lip. Press the bag slightly against the anterior portion of the mentum with one hand. With the other hand, wrap the excess bag under the patients neck (do this one side of neck at a time). Small dividers should be placed on each side of the neck making sure the bag is kept as close to the skin as possible. The dividers are to be placed in the vertical slots as shown in Diagram 1.

    Step 9 – Wrap each side of the plastic bag around each arm and tuck under the posterior surface of each upper extremity. Place the longest divider boards beside the patients arms that are enclosed by the bag. The closest slot should be used to assure a tight fit around the upper arms. The area of the plastic bag around the shoulders should be wrapped under the shoulders with dividers placed parallel to the clavicles in the horizontal slots of the slotted board. The smallest dividers should now be placed around the periphery of the bag and patient as illustrated in Diagram 1.

 

(diagram)

 

Diagram 1

 

    Step 10 – The additional board and spirit level are now used to verify the flatness of the anterior ALPHA CRADLE^® form. Place the additional board on top of the anterior segment of the bag, keeping the board at rest on the shoulder and anterior chest area. This area should now exhibit some excess foam volume, but the board should not lay over this area. Instead, the board should lie directly underneath the patients chin (The chin will rise with the foaming agents). Next place the spirit level on the additional board keeping its long axis parallel across the patient from right to left (i.e. crosswise). Keep one hand on one side of the additional board, and the other hand on the opposite side of the additional board. Balance the additional board on the patients chest until assurance that the level surface condition is demonstrated. The level surface is critical after the patient is turned prone for simulation and daily treatment.

    Step 11 – (OPTION) If a level is not available, then lateral isoline lasers in the simulator room can be used to demonstrate a level condition. Instead of the level, simply raise the simulator table until the lateral isoline lasers skin the top of the additional board from both sides of patient. Adjust the additional board and table height until the isoline lasers are coincident with the boards surface as illustrated in Diagram 2. Caution, before attempting to use the isoline method, be sure to verify that the laser lines are directed parallel with the long axis of the simulation table.

 

(diagram)

 

Diagram 2

 

    Step 12 – The patient will be required to stay still in the level position for at least ten minutes. During this time it will be necessary to hold or support the additional board in the level condition throughout this time period until the form is hardened. After it has sufficiently hardened the form is ready for removal.

    Step 13 – Next turn both the ALPHA CRADLE^® form and additional board over so that the flat surface is in direct contact with the simulator table surface. The form is now ready to receive the patient in the prone position.

 

Part Two – Patient Forehead Immobilization

    The need to flex the chin down into the suprasternal notch of each patient creates a different distance between the simulator table surface and the patients occipital while the patient is in the supine form fabrication position. Once the form with additional board is used for prone treatment a gap between table surface and forehead exists. To immobilize the head region and compensate for the distance from forehead to table, an individual forehead rest is designed in Styrofoam^® for each new patient. Styrofoam^® is inexpensive and readily available in the majority of radiotherapy centers where low melting allow beam restrictors are used.

    Step 1 – Place the child prone into the modified form. Be sure the patients arms are by the child’s sides and that the palms of their hands are touching the lateral pelvis. The child’s chin must be tucked into the groove created during fabrication flexion. In addition, place a 45° angle support sponge under the patient’s ankles for comfort and support during simulation, port filming, and daily treatment. If an angle sponge is unavailable at your facility, several wrapped sheets can be used instead.

    Step 2 – The Styrofoam^® piece mentioned in the supplies needed section earlier should now be placed directly in front of the patient forehead. Using a magic marker, outline the contour of the patients forehead on the side of the Styrofoam^®. This will establish a beginning reference for shaping the Styrofoam^® to each patients particular shape. Once the Styrofoam^® is appropriately shaped and accurate, line the headrests/patient interface with masking tape and adjust until the patient is comfortable with it.

    Step 3 – Place the customized forehead rest on the table and have the child tuck his/her chin down to fit the ALPHA CRADLE^® chin saddle resting his/her forehead on the rest. There should not be any space between the forehead and the custom forehead rest at this point. If the child is uncooperative, there may be the need to secure the head and forehead rest attaching a piece of masking tape to the simulator or treatment unit table.

    Step 4 – At this point you are ready to ask the parent or guardian to leave the room, make any adjustments to the form that might be necessary, and begin the simulation process.

 

SUMMARY

    We have modified and refined the ALPHA CRADLE^® Patient Repositioning System to enhance patient comfort and treatment, as well as alleviate anxiety by allowing the initial form construction process to take place in the supine rather than the final prone treatment position. Using only a few additional readily available tools such as an additional board, a level or lateral isoline lasers, we have been able to produce a modified immobilization device which after fabrication will: 1) guarantee a flat table/patient treatment surface, 2) be light weight and easily moved from one treatment room to another, 3) fills the immobilization requirement by sealing the patient tightly within the form’s grip, 4) demonstrates minimal anterior to posterior spine displacement, and 5) assure on a daily basis geometric dosimetric reproducibility.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER SIX

 

 

REPOSITIONING AND IMMOBILIZING THE TORSO REGION

(cover page)

 

ALPHA CRADLE^® PATIENT REPOSITIONING SYSTEMS:

HS1, HS2, HS3, AT1, AT2, AT3, PT1, PT2, PT3, PHS1, PHS2, PHS3, HS2M, HS2M-E

    Smithers Medical Products, Inc. offers over 15 different anatomical forms for immobilization and repositioning of the torso region. These forms include our adult and pediatric head and shoulder forms, thorax forms, and our newer extended forms. These forms offer a wide assortment in the treatment of the torso region.

    As with the other forms, it is important to keep the foam tight against the patient for the most effective customized form. When treating a patient AP/PA, do not hesitate to cut the desired treatment port to the width needed. Many times people hesitate to cut the port needed because it may seem so large that the medical professional wonders if the form will still be useful. But remember, it’s the sides of the form that reposition and immobilize the patient, not the base. When ports are cut in the base, remember to use a damp cloth and wipe the form off removing any particles of foam that may have collected. Use cloth or paper tape to cover the area of exposed foam. Be sure to index the form with a marker, corresponding to the form’s position with the lasers. This will assure that your form is in the same position on a daily basis relative to the isocenter.

 

ACMMII

    When making forms on this area of the anatomy, do not place extra pieces of polystyrene inside the bag to increase the base durability. Instead, concentrate on making the sides of the form strong, durable and tight against the patient. As ports are usually cut in these forms for AP/PA treatment, the thin base is easily cut out from the form, often only requiring the use of a pair of scissors. Index the form to the corresponding laser mark with a marker. Remember to tape the edges of the cut out port to make the form comfortable for the patient (i.e. no sharp edges).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Minimizing Radiation Dose to the Heart Through Use of the Alpha Cradle^® Positioning Device

 

John J. Smith, BA, RTT

Gary J. Schreiber, MD

St. Francis Hospital

Evanston, Illinois

(cover page)

 

MINIMIZING RADIATION DOSE TO THE HEART THROUGH USE OF THE ALPHA CRADLE^® POSITIONING DEVICE

John J. Smith, BA, RTT

Gary J. Schreiber, MD

St. Francis Hospital

Evanston, Illinois

 

INTRODUCTION

    The role of radiation therapy for non-small lung cancer is controversial. Weisenberger et al¹ in the randomized Lung Cancer Study Group trial noted no increase in survival but did note an increased control of intrathoracic disease for patients with Stage II or III disease. Van Houtte found a decrease in survival in patients without nodal metastasis when given post operative radiation following pneumonectomy.² One of the arguments in favor of treating patients in the adjuvant setting is that the treatment of mediastinal recurrences is more difficult both technically as well as physically because of patient morbidity. The increased morbidity is in part related to increased volume of normal cardiac tissue incidentally included in the treatment volume. The increased volume can lead to higher risk of pericarditis and cardiac dysfunction. This case demonstrates the ALPHA CRADLE^®

Patient Repositioning System can be used to immobilize patients and naturally displace some of the cardiac silhouette from the treatment volume.

 

METHODS AND MATERIALS

    In December of 1992 E.P. a 70 y/o female with a 25 pack year smoking history presented with wheezing and dyspnea, a CXR was obtained and confirmed the presence of an abnormal mass in the left lung. Workup revealed a squamous carcinoma of the left upper lobe. No evidence of adenopathy or distant metastasis was found, after staging with CT scans and bone scans. A complete left pneumonectomy was performed.

    Mediastinal lymph node sampling was negative for spread of local disease, therefore no adjuvant therapy was indicated at that time. In July of 1993, the patient developed some hoarseness, and was seen by the ENT surgeon, who found a left true vocal cord paralysis. CAT scan of the chest was consistent with a mediastinal recurrence of her primary lung carcinoma. No other evidence of metastatic disease was noted. A CT-guided biopsy confirmed the recurrent malignancy.

    This patient’s course of radiation therapy presented somewhat of a challenge. After removal of her left lung the cardiac structures took the path of least resistance. The heart in its entirety now occupied the mid portion of the left chest cavity just behind the area of this patient’s bulky recurrent disease. A dose 4000 cGy was planned to the left hemithorax with a boost of 2000 cGy to the residual disease. A CT of the chest prior to initiation of the RT confirmed that the cardiac structures would hinder the attempt to carry the prescribe dose to eradicate her recurrent lung disease. With the risk of heart complications an alternative method of treatment was necessary. The conventional supine parallel opposed fields would require that the complete heart volume would receive the same dose as the recurrent lung tumor in the left hemithorax. A positioning alternative was then attempted. The patient was positioned in the right lateral decubitus with the hope that the cardiac structures would shift toward the mid-line thus removing a portion of the healthy cardiac structures from the target volume. With the use of an ALPHA CRADLE^® immobilization shell, a precise simulation was accomplished with the patient in a comfortable, secure position. The ALPHA CRADLE^® form supported her shoulder, thorax and upper abdomen (Fig. 1,2). Once the simulation was complete, a CT simulation was performed with the patient in the supine position, as well as the right lateral decubitus position for comparison. As hoped, there was a significant anatomical change between the two positions. A favorable shift of the cardiac structures with the patient in the right lateral decubitus helped isolate the structures without compromising the tumor volume. Volume isodose plans were performed and confirmed that the cardiac structures would receive 25% less dose with the patient in the right lateral decubitus position (Fig. 3, 4).

 

(diagram)

 

Fig. 1 Patient is comfortably supported.

 

DISCUSSION AND SUMMARY

    Frolich³ in his discussion of radiation effects notes that cardiac radio-reactions can be transient or harmless and rarely can lead to acute left-threatening situation. However, long term morbidity from cardiac irradiation has been well documented. Radiation pericarditis and premature coronary artery disease have been described by Arsenian.⁴  Because significant curative therapeutic results can be obtained with radiotherapy in thoracic area and the chances for curing increase for many patients, a slight risk is justifiable for side effects on healthy adjoining tissue. On the other hand undesirable side reactions can influence the life-quality of the tumor cured patients, therefore, the aim of the radiation oncology team is to achieve uncomplicated local-regional control of cancer by radiation therapy. To accomplish this goal, precise knowledge of tumorcidal dosages and tolerance of doses of various normal tissues is most important. Unfortunately, after eight decades of radiotherapy practice, current knowledge of tolerance dose for healthy tissue an optimum curative dose for malignant tissues is still somewhat imprecise. In recent years, sophisticated treatment planning systems have been implemented. Actual CT images with the target and tumor volume superimposed with isodose curves representing the cumulative dosages of radiation to the tumor have aided in precision treatments. This advancement has resulted in major improvements to ensure adequate tumor coverage and better spacings of critical and normal structures. With the use of immobilization devices such as ALPHA CRADLE^® brand Patient Repositioning Systems, positioning alternatives and treatments can be personalized under any circumstances. In this particular case the heart dose was reduced by 25% without compromising the dose to the lung tumor. It is our intention to use ALPHA CRADLE^® forms on all patient procedures when a positioning variation is used.

 

(diagram)

 

Fig. 2 Form Provides support while creating reproducibility.

 

(diagram)

 

Fig. 3

 

(diagram)

 

Fig. 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stabilization Device For Patients Undergoing Radiation Therapy For Hodgkin’s Disease

 

 

Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

(cover page)

 

STABILIZATION DEVICE FOR PATIENTS UNDERGOING RADIATION THERAPY FOR HODGKIN’S DISEASE

By Gunilla C. Bentel, RN, RTT

Duke University Medical Center

Durham, North Carolina

 

INTRODUCTION

    Hodgkin’s disease is a quite curable disease which strikes approximately 7400 young Americans annually, the majority of them less than 35 years old. This disease, which earlier was considered fatal, is now always considered curable in previously untreated patients. Great progress has been made in multi-disciplinary management of Hodgkin’s disease can be attributed to improved radiation therapy techniques. The ability to customize the shape of the treatment fields, the ability to treat contiguous lymphatic sites in a single field, and the capability to treat these large opposed fields without having to change the patient’s position represent some very important improvements. Improved diagnostic technologies also play an important role in the determination of the spread of the disease and, thus, aid in the choice of treatment strategy.

    Appropriate treatment decisions in the management of cancer is always important for successful outcome but, in the management of Hodgkin’s disease, it is especially critical. The radiation dose prescription for Hodgkin’s disease presents a dilemma in which a balance must be struck between two conflicting end points: the use of doses high enough to eradicate the tumor and low enough to cause little or no injury to normal tissue. Serious attention must therefore be given to precision in the delivery of the often complex radiation therapy treatment in these relatively young and curable patients.

    Marks and Haus has presented data with respect to misalignment of treatment fields in patients with Hodgkin’s disease and non-Hodgkin’s lymphoma.^5,9,10 They found, in a retrospective review of port films of 902 set ups on 99 patients with Hodgkin’s disease and other lymphomas, that 36% of the treatment fields were erroneously placed. In 10 of 99 patients disease was not controlled locally. Two of these failures were at the margins of the fields and were shown by portal films to be correlated with positioning errors leading to reduced dose at the sites of recurrence. One might conclude that errors in treatment delivery including immobilization errors, may be a significant cause of marginal recurrences.

    Taylor et al. found 15% of mantle fields in error by more than 5 mm in 28 patients (1186 films).¹⁴ There was no tumor or prophylactic treatment area shielded in these misaligned fields. Only 1% of the fields studied was considered unacceptable. The anterior field was treated with the patient supine and immobilized using a bite block and face mask system while the posterior field was treated with the patient prone and positioned in an ALPHA CRADLE^® form.

    Hulshof et al. studied 216 set ups of mantle fields and found that on the first port film, at the start of the treatment, 13% of the set ups were in error by more than 10 mm.⁶ Following the first correction, an adequate treatment set up was obtained in 60% of cases and after the second correction the adequacy rate was 84%. Creutzberg et al. compared 94 megavoltage portal films with 26 simulation films and found that alignment errors in excess of 10 mm occurrence in 7.2% of cases.² Other authors have attributed small errors observed on the initial portal field to discrepancies between alignment systems in the simulator room and the treatment room.^{3,4,7,11,12,13} Both Hulshof and Creutzberg reported a larger error rate observed on posterior fields treated with the patient in the prone position. Maintaining the patient’s position supine for all fields improves not only the reproducibility but it also improves the dose uniformity across the junction of adjacent fields.

Kinzie et al.⁸ in a Patterns of Care study, reviewed port films of patients treated with radiation therapy alone. They found that inadequate margins were associated with a 54% overall relapse rate, of which 33% were in field or marginal recurrences. When the port films were judged to be adequate, the overall relapse rate was 14% with only 7% being in-field or marginal recurrences.

    Reproducing the treatment fields precisely on a daily basis in order to avoid “geographic misses” and to minimize the volume of normal tissue being irradiated is crucial. Aggressive immobilization should be utilized to offer these patients the best possible chances for cure. Failure to controls the disease on the first attempt often constitutes a life-threatening situation for the patient. Judicious implementation of the initial treatment is therefore crucial. Further radiation therapy which may be necessary to treat recurrent disease is limited by the tolerance of the adjacent normal tissue and will increase the risks of long-term adverse consequences.

 

TREATMENT

    The extent of radiation therapy in Hodgkin’s disease depends on the stage of the disease but it involves almost always total lymphoid irradiation (TLI) or subtotal lymph nodal irradiation. The lymph nodal groups above the diaphragm are the cervical, supraclavicular, infraclavicular, axillary, mediastinal, and hilar nodes. These are usually treated through large opposed anterior and posterior fields referred to as mantle fields.

    In adult patients, the mantle field is often very large. The margins extend cephalad to include the submanibular nodes, caudal to the level of the diaphragm and lateral to include the axillary nodes. The field is shaped by customized shielding blocks which protect the lung parenchyma, the humeral head, and the distal part of the humerus bilaterally. Additional shielding blocks are added at appropriate dose levels to protect the left ventricle of the heart, the larynx and the cervical spinal cord.

    The lymph nodal groups below the diaphragm are the para-aortic, pelvic, and inguinal lymph nodes. The splenic pedicle (or spleen, if it is in-situ) is also usually treated depending on the findings during a staging laparotomy. These lymph nodes are also usually treated through parallel opposed anterior and posterior fields. Depending on the stage of the disease, the pelvic and infuinal lymph nodes may not need to be treated. Fields designed to include the nodal areas below the diaphragm includes a very large volume of bone marrow, which, if treated concurrently, often causes hematopoietic depression. The para-aortic lymph nodes and the splenic pedicle are therefore often treated first and the pelvic and inguinal nodes are treated following a recovery period. These fields are also custom designed, using shielding blocks to protect as much as possible of bone marrow, liver, kidneys, bowel, and bladder.

    The customized shielding blocks used in the treatment of the mantle and para-aortic-splenic fields are fixed to a tray which fits tightly into the collimator of the therapy machine. When the tray holding the blocks is inserted correctly in the beam, the treatment field is projected precisely as it was outlined on the radiograph from which it was formed. The only variables in the treatment geometry is the orientation of the treatment machine and the couch and in the patient’s position. The machine and couch variables can easily be eliminated by setting the prescribed angles while the variation in the patient’s position is more difficult to master. The large perimeter of the mantle and para-aortic/pelvic fields are very sensitive to small errors in misalignment between the radiation beam and the patient’s anatomy. An alignment error, which can occur even if the central axis of the beam is correct, becomes more severe as the distance from the central axis increases as shown in Fig. 1. Therefore, since the treatment fields used in the treatment of Hodgkin’s disease often are large, the patient-beam alignment is very important when these fields are treated.

 

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Fig. 1 A treatment field can be misaligned even when the central axis is set up correctly. The effect of a misaligned field increases as the distance from the central axis increases.

 

    As described above, the lymph nodal areas are often treated sequentially in two or three adjacent areas through opposed fields leading to difficulties in matching field borders without causing overdosage at the field junctions. The use of the immobilization device described here reduces misalignment errors and also reduces the risks of inadvertent mismatch of the adjacent field margins.

 

POSITIONING DEVICE

The Patient’s Position

    The patient’s position is supine with the arms raised above the head and the chin extended. This position is maintained during the treatment of all fields to minimize changes in the relationship between skin marks and the spinal cord near the field junctions. The extension of the chin allows the submental, submandibular, and cervical lymph nodes to be treated while keeping the oral cavity out of the treatment field. The arms are elevated in an effort to move the axillary lymph nodes out and away from the lung parenchyma. This allows shielding of the lung tissue while the margins around the axillary lymph nodes are increased.

    An uncomfortable position is quite difficult to maintain for long periods of time. Therefore, it is fundamental to successful immobilization that the patient is provided with supports that will make the position comfortable. Such a device should also aid in reproducing the position from day-to-day. ALPHA CRADLE^® forms (HS2) for positioning patients receiving radiation therapy for Hodgkin’s disease has been used in our clinic for approximately 15 years. The HS2 ALPHA CRADLE^® form consists of a Styrofoam^®* form which provides indentations for the elevated arms (45°) and offers a barrier for the foam around the patient’s head and thorax. The foam, when prepared and used as directed by Smithers Medical Products, Inc., fills the space between the Styrofoam^® and the patient’s skin and forms a perfect mold in which the patient can be repositioned for each treatment. This ALPHA CRADLE^® form, which only reaches to the patient’s waist and offers no comfortable place for the patient to rest the hands, was used in our clinic for approximately 10 years. The difficulties with field alignment were reduced, particularly when the mantle fields were treated, but not to our satisfaction. Since this ALPHA CRADLE^® form offered no reliable method by which to reproduce the arm elevation, a handle which the patients hold onto during the treatments, was added.¹ Reproducing the arm elevation precisely each day reduces the risk of the skin marks moving and overlay different internal anatomy. An improvement in set up reproducibility of the mantle fields was observed, while the difficulties with reproducing the para-aortic/pelvic fields continued. More recently, another modification, described in this report, has been made to the HS2 ALPHA CRADLE^® form.

 

*Registered by Dow Chemical

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Fabrication of the immobilization device

    The set up difficulties which we continued to experience was thought to be the result of only the chest being aligned with the sagittal alignment line when the mantle field was treated, or the abdomen when the para-aortic nodes were treated. The immobilization device was therefore extended caudally to also immobilize the pelvis and the thighs and so that the sagittal alignment line could be marked on the immobilization device at two points separated by a long distance (Fig 2).

 

(diagram)

 

Fig. 2 The Alpha Cradle^® form extends to the knees in most adult patients making it possible to make alignment marks (arrows) both above the head and between the knees.

 

    The standard ALPHA CRADLE^® form with the grooves for arm elevation at 45° is modified to include a base which is 5’ long. This base extends to just below the knees in most adult patients. Several pieces of Styrofoam^® are cut and added to the base at points which are determined with the patient in the form but without the foam. A rectangle of Styrofoam^® approximately 2” wide, 4” long, and 1” high, is placed in the center of the ALPHA CRADLE^® base between the patient’s knees (Fig. 3A). The foam will raise up between the knees and form an elevation which is used for marking the sagittal alignment line (Fig. 3B).

    The second sagittal alignment mark is made on the Styrofoam^® form above the patient’s head. These two alignment marks are used in the daily repositioning of the patient on the couch. A small triangular-shaped Styrofoam^® block is placed under each knee to relax the patient’s back. Two Styrofoam^® cylinders, approximately 3” long and 1” in diameter and formed from the Styrofoam^® used for customized block cutting, are placed in a separate bag which is positioned where the patient’s raised arms and hands will be positioned. A retaining wall of Styrofoam^® is added to each side of the base to help force the foam in toward the patient’s torso.

    With the patient removed, each piece of Styrofoam^® is taped to the base and the entire ALPHA CRADLE^® form is placed inside a large protective polyvinyl bag. Before the patient is returned to the mold, one set of foam (660 cc)* is prepared as directed by the manufacturer. Approximately 100 cc is poured inside the arm support bag holding the Styrofoam^® cylinders and the remainder is evenly distributed inside the form. Several small holes are made in the arm support bag on the side which is toward the Styrofoam^® form to allow some foam to leak and form a glue which attaches the small bag to the rest of the mold. Alternatively, a small amount of foam can be poured on top of the Styrofoam^® form under the smaller bag. If the bag with the handles is not attached to the HS2, it can move causing problems with repositioning of the arms.   

 

(diagram)

 

Fig. 3A Several pieces of Styrofoam are added to the HS2 Alpha Cradle^® form. The dark bag seen near the head segment of the Styrofoam form is for the arm support and handles. The entire form and the dark bag are placed inside the larger bag before the foam is poured.

 

*In some patients it may be necessary to use an additional 250 or 375 cc of foaming agents.

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Fig 3B The finished Alpha Cradle^® form creates a comfortable, tight fitting mold for the patient.

 

 

    After approximately 60 seconds, during which time air is allowed to circulate inside the bag, the air is squeezed out, the bag is sealed, and the patient is returned to the form. The patients enter the form body first sitting on the couch near the caudal edge of the ALPHA CRADLE^® form and then gradually lift and move the buttocks over the knee supports and into the form. A visual check is made to see that the patient appears straight on the mold and they seed that the patient appears straight on the mold and they are asked to adjust the chest and hips until they feel straight. The patient’s arms are elevated to desired position and the Styrofoam^® handles are moved into the patient’s hands. The foam is pushed up around the hands and the arms. Masking tape is fastened to the sides of the ALPHA CRADLE^® and is stretched across the patient’s body to force the two sides in toward the patient to form a tight-fitting mold. Foam is also forced up between the patient’s knees where the sagittal alignment line is later marked. A chinstrap, made of Velcro^®**, is used to aid the patient in maintaining the chin extension.   

   

**Registered by Velcro USA

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A board, which is wider and longer than the ALPHA CRADLE^® form, is placed on top of the couch before the ALPHA CRADLE^® form fabrication is initiated to prevent leaking foam from forming a lip over the couch. Such lip or other irregular surface under the ALPHA CRADLE^® form and consequently of the patient giving rise to field misalignments.

    The foam stops expanding after approximately 7-10 minutes but requires an additional 10 minutes to become firm. During this time, the patient is asked to think about how it feels to lay in the mold so that when they are repositioned, they can adjust their body until it feels the same.

    To produce a tight-fitting mold, it is important that the patient wears minimal clothing during the ALPHA CRADLE^® form fabrication. Since patients usually wear different clothing each day during the course of treatment, the mold may be too large some days and too tight on other days. Both situations would compromise the ability to correctly reposition the patient.

 

PATIENT-BEAM ALIGNMENT

    Prior to the simulation procedure it is crucial that the machine settings, i.e., the couch, collimator, and gantry angles are all sat to 0°. The sagittal alignment line is marked in the patient’s midline which is found either by palpation of the sternum and pubis symphysis or by viewing the spinal column in fluoroscopy. The sagittal alignment line is also marked on the elevation of the ALPHA CRADLE^® form between the patient’s knees and on the positioning device above the patient’s head. If the polyvinyl bag is not fixed to the mold, it is best to peel it away and make the marks directly on the foam eliminating any chance that the mark may move. Since many alignment systems are less reliable farther from the isocenter, it is necessary to move the couch so that each of the two marks are made near the isocenter, i.e., move the couch out from the gantry to make the mark above the head and move in toward the gantry to make the mark between the knees.

    The treatment fields are then simulated in the usual fashion and the fields are marked on the patient’s skin surface. The transverse sand lateral (horizontal) alignment lines are marked on the ALPHA CRADLE^® form to aid in the treatment set up in the even that the marks on the skin are worn off or migrate during re-marking each day. By aligning the four alignment lines with the marks made on the ALPHA CRADLE^® form, the position can be reproduced for each treatment without marks on the patient’s skin. The caudal extent of the mantle field is tattooed on the patient’s skin on the anterior chest to aid in setting the gap between the mantle and the para-aortic fields when the patient returns 2 to 3 weeks later.

    When the patient returns for the para-aortic/pelvic treatment, the position is resumed in the same ALPHA CRADLE^® form. A gap is calculated between the mantle and the para-aortic fields. During the simulation of the para-aortic field, a lead marker is placed on the tattoo indicating the caudal margin of the mantle field. If the gap is sat correctly, the cephalad margin of the posterior para-aortic field should traverse the spinal column at the same level as the caudal margin of the anterior mantle field (Fig. 4). The para-aortic field is also tattooed on the patient’s abdomen and in the case of subsequent pelvic/inguinal node irradiation, the gap is similarly determined and marked.

    All treatment fields are defined by customized blocks and are treated using a linear accelerator*. Mantle fields are treated using a 6 MV photon beam while in some patients the para-aortic fields are treated using 15 MV photons. The patients are invariably treated in the supine position, i.e., the posterior beam traverses the ALPHA CRADLE^® form. No adverse skin reaction has been noted and no correction for attenuation by the foam material has been made. All fields area treated using an isocentric technique except if an extended distance is required in order to include the entire treatment area in a single field.

 

*Siemens Medical Systems, Inc

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Fig. 4 A gap between the mantle and para-aortic fields calculated so that all beam edges converge at the mid-depth provide the most uniform dose distribution. Although it appears, when looking at the radiographs of the two anterior fields, as if the fields overlap in the spinal column, the dose there is low because this area lies in the exit of both beams and are outside both of the posterior fields. The segment of the spinal column “seen” in the anterior mantle field should be outside the posterior para-aortic field when the field gap is sat correctly.

 

PORT FILM REVIEW

    The reproducibility of the patient-beam alignment is documented through weekly port films. On the first treatment day, port films are taken of both the anterior and the posterior fields. If no misalignment is noted, subsequent port films are taken of the anterior and posterior fields on alternate weeks. If a misalignment is noted, a correction is made on the following treatment and another port film is taken.

    Small discrepancies between alignment systems in the simulator room and the treatment room and varying amount of sag in the two couches may cause small errors in patient alignment on the first set of port films^{3,4,7,11,12,13}, however, in evaluating the effect of the extended ALPHA CRADLE^® form described above, all port films were included. To assess the effect of the extended ALPHA CRADLE^® form described in this report, only the monitoring physician’s routine review of port films was used. When a port film was taken of the anterior and the posterior fields on the same day, it was recorded as only one port film day since it represented only one set up.

 

PATIENT CHARACTERISTICS

    To assess the effect of the extended ALPHA CRADLE^® form, the number of misalignments observed on port films was compared with that of the same number of patients treated using an ALPHA CRADLE^® form which had an arm support and handles but extended only to the waist. Ten patients with Hodgkin’s disease were treated between February and August 1993, using the HS2 ALPHA CRADLE^® extended form. These 10 patients represented 53 mantle port film days and 22 para-aortic or para-aortic/pelvic film days. The earlier group of 10 patients were treated between April 1992 and January 1993 and represented 63 mantle port film days and 42 para-aortic or para-aortic/pelvic film days. In both groups, other fields were also treated (Waldeyer’s ring, mediastinal boost, inguinal nodes, etc.) however, these fields were not included in the analysis due to the inability of matching these fields in the two groups. It would not be a fair evaluation of the effect of the extended ALPHA CRADLE^® forms if the patients with which to compare the set up accuracy had been selected such that the two groups would have the same treatment fields. The patients in the earlier group represented the 10 Hodgkin’s disease patients treated immediately prior to the implementation of the extended ALPHA CRADLE^® form.

 

RESULTS

    Review of the mantle port films revealed that the set up reproducibility was excellent in both groups with a 6.3% misalignment rate (4 in 63 set ups) in the group using the short ALPHA CRADLE^® form and 5.7% (3 in 53 set ups) in the group using the extended HS2 ALPHA CRADLE^® (HS2-M) form.

    In the para-aortic or para-aortic/pelvic port films, there was a 42.9% misalignment rate (18 in 42 set ups) in the group using the short ALPHA CRADLE^® form and 9.1% (2 in 22 set ups) in the group using the extended ALPHA CRADLE^® form.

    The overall misalignment rate was therefore 21% (22 in 105 set ups) in the group using the short ALPHA CRADLE^® form and 6.7% (5 of 75 set ups) in the group using the extended ALPHA CRADLE^® form. The size of the misalignment errors, as indicated by the monitoring physician, was larger in the group using the short ALPHA CRADLE^® form with 5 being > 10 mm while in the group with the extended ALPHA CRADLE^® form all shifts were < 5 mm.

    It is interesting to note that two of the three set up errors in the mantle treatment and one in the para-aortic treatment in the group using the extended HS2 ALPHA CRADLE^® form, occurred in the same patient. The patient was a young male who was non-compliant with the treatment schedule and came for treatment on an irregular basis. The only other set up misalignments in this group was a 5 mm shift in a mantle fields and a 3 mm shift in a para-aortic field.

    In addition to finding these convincing numbers, the technologists feel that they can set up the treatment faster when the patients are positioned in a body mold. The reduced number of repeat port films also saves the technologists’ time, both in terms of taking and developing the films, and it also reduces the physicians’ time because there are less port films to review. Other savings are recognized in terms of amount of films needed and in space required for film storage. The most important gain, however, lies with the fact that the patients’ feel comfortable and relaxed with the handles and are secure on the narrow treatment couch.

 

DISCUSSION

    Radiation therapy in the often young and curable patients with Hodgkin’s disease require careful planning and implementation. Long term adverse consequences of the treatments must be minimized by sparing as much as possible of adjacent normal tissue. Serious attention must therefore be given to the precision with which the treatments are delivered. Aggressive immobilization techniques may reduce set up errors and lead to improved survival. The ALPHA CRADLE^® form, HS2-M Extended, described in this report represent one improvement which may have a role in the final outcome of the treatment for patients with Hodgkin’s disease.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Kyphotic Treatment Set Up:

Immobilization and Flattening Techniques Using Alpha Cradles^®