ALPHA CRADLE® DEVICE AND PLASTER BANDAGE POSITIONING PATIENTS FOR CRANIAL-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. To fabricate an Alpha Cradle device, 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.

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® device. 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® device. Open the plastic bag and lay it over the cast (Fig. 3).

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

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).

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).

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® device must reach the board and flatten against it! Allow the ALPHA CRADLE® device to harden, as directed. After hardening, remove the top board. What will be seen is the flat surface of the ALPHA CRADLE® device. 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® device and a cast cutter is helpful for the plaster.

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).

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® device. 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).

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® device 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® device 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® device 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® device 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® device 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.