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Fabrication of bolus compensators used in the treatment of irregular tissue surfaces in radiation therapy
Fabrication of bolus compensators used in the treatment irregular tissue surfaces in radiation therapy
of
Carl F. Driscoll, DMD,* Michael A. Taylor, MS,b and John S. Ostrowski, DMDc Tripler Army Medical Center, Honolulu, Hawaii; and National Naval Dental School, Bethesda, Md. Radiation
involving irregular surfaces of facial topography often causes treatment difficulties for the radiation oncologists. The isodose curves normally used become skewed, thereby making treatment planning more complex. A simple and useful technique is presented describing the use of dental materials to make a bolus compensator to aid in radiation therapy of nonplanar surfaces. This technique will allow the radiation oncologist to treat these patients in a most efficient manner. The materials needed are readily available to the dentist and are easily handled. (J PROSTHET DENT 1992;67:370-4.)
I
n 1990, the American Cancer Institute estimated that the number of new head and neck cancer patients would grow to over 42,000 patients.’ One possible mode of treatment for these new cancer patients involves the use of ionizing beams or radiation therapy administered separately or in conjunction with surgery or chemotherapy. The dental profession has long played an active role in this treatment modality by improving and maintaining the oral health of the patient prior to, during, and following the administration of radiation treatment.2-8 Fabrication of radiation positioners and shielding devices are two examples of dental contributions to the treatment of patients undergoing radiation therapy. Another aspect of radiation therapy where dental assistance can be used is in making bolus compensators. The purpose of bolus compensators is to improve the quality of the radiation beam in treating irregular surfaces of the facial topography.g-12 Radiation beams are evaluated with respect to isodose curves that are based on measurements made in a phantom of unit density material having a flat surface perpendicular to the long axis of the beam.g, l3 When the beam enters a nonplanar surface, such as the irregular surface of the face, a skewing of the isodose curve results (Fig. l).‘, l4 This
The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army, the Department of the Navy, or the Department of Defense. BLieutenant Colonel; Chief, MaxiIlofacial Prosthodontics, U.S. Army DENTAC, Tripler Army Medical Center. bCommander; Chief, Medical Physics, National Naval Medical Center. %aptain; Chief, Maxillofacial Prosthodontics, National Naval Dental School. 10/l/26665
370
Fig. 1. Skewing of isodose curves from posed beams on irregular surfaces.
Fig. 2. Effect of bolus compensator with same beams as in Fig. 1.
MARCH1992
bilaterally
on isodose
VOLUME67
op-
curves
NUMBER3
FABRICATION
OF BOLUS
COMPENSATORS
Fig. 3. Cast. trimmed blocked out with clay.
to desired
size and undercuts
Fig.
Fig.
4. Cast and bolus compensator.
Fig.
5. Bolus compensatorin place.
phenomenonrenders the standard isodosecurves ineffective, thereby complicating treatment planning.gv12+ l4There is a needto convert irregular tissuecontours into a flat surface perpendicular to the central axis of the ionizing beam (Fig. 2)g-13to more accurately apply these isodosecurves.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
6. Cast with outline of lesion and treatment region.
The useof the boluscompensatorhaslong beenknown, but the technique of easy fabrication at a reasonablecost has not been adequately addressed. The literature is replete with suggestedbolus compensatormaterials and techniques.However, someof thesetechniquesrequire the useof sophisticatedthree-dimensionalmilling machinesor holographic image recorders that are beyond the budget and/or capacity of many radiation therapy facilities.g-21 Without these sophisticateddevices,the production of accurate bolus compensatorsbecomesvery difficult. Often, the radiation oncology personnel must attempt to make their own devices using crude techniques, with lessthan ideal results. One drawback mentioned with respect to this type of tissue boluscompensatoris the lossof the skin-sparing effect of the ionizing beam when the bolus compensator is placed immediately adjacent to the skin.g,17,2oHowever, when one is treating superficial lesions,the skin-sparing effect may not be desirablebecausethe radiation oncologist requiresthe maximum beameffect to be at the level of the skin or just below it, as in the treatment of basalcell carcinomasor Kaposi’s sarcomas.15, 22 This article describesa simple and effective technique for making boluscompensator.The boluscompensatorwill
371
DRISCOLL,
Fig. 7. First section of bolus compensator rating
TAYLOR,
AND
OSTROWSKI
made incorpo-
undercut.
Fig. 9. Sections tried on individually gether (B).
(A) and then to-
aid the radiation oncologist in the treatment of superficial lesions of the faee with irregular contours. Two patients presented illustrate the fabrication and positioning of the bolus compensator.
TECHNIQUE One-section
Fig. 8. Duplicated compensator.
cast including
first section
of bolus
bolus
compensator
1. Make a moulage of affected and adjacent tissues. 2. Have the radiation oncologist and physicist outline the desired dimensions (width, length, and depth) of the bolus compensator. 3. Trim the stone cast to the desired size of the treatment region and block out undercuts with clay (Fig. 3). 4. Box the cast using masking tape, and lubricate. 5. Pour molten wax into the boxed cast, allow to harden, and separate (Fig. 4). Adjust the height to the desired dimension. This pattern can be flasked and processed with methylmethacrylate resin if desired.
MARCH
1992
VOLUME
67
NUMBER
3
FABRICATION
OF BOLUS
COMPENSATORS
and withdrawal. Visualize the design to allow for placement as well as obliteration of the undercut. 4. Lubricate the cast and fill undercuts with wax to the desired shape (Fig. 7). This step may entail two or more sections. 5. Duplicate the cast (Fig. 8). 6. Box the duplicated cast and lubricate. 7. Flow molten wax onto the duplicate cast and allow the wax to harden. Adjust the height to the desired dimension. a. Position the individual wax sectionson the master cast to ensureproper fit. 9. Position the bolus compensatoron the patient to assure accuracy (Fig. 9). 10. Handles and interlocking sectionsmay also be required (Fig. 10). CONCLUSIONS A simpleand effective technique to aid the radiation oncologist in treating the irregular surfacesof the face of head and neck cancer patients hasbeen described.The materials are readily available and are easily handled. Further evaluation of the effectivenessof various dental materials for use as bolus compensatorsis currently being investigated.
REFERENCES
Fig. 10. A, B, and C, Handles and interlocking sections are sometimesrequired.
1. American Cancer Societv. CA 1990:40:18-21. 2. NIH consensus statement. National Institutes of Health consensus development conference statement. Oral complications of cancer therapies: diagnosis, prevention, and treatment. J Am Dent Assoc 1989; 119179-83. 3. Beumer J, Curtis TA. Radiation therapy of the head and neck tumors: oral effects and manifestations. In: Beumer J, Curtis TA, Firtell D, eds. Maxillofacial rehabilitation. St Louis: CV Mosby Co, 1979. 4. Rothwell B. Prevention and treatment of the orofacial complications of radiotherapy. J Am Dent Assoc 1987;114:316-22. 5. Engelmeier RL, King GE. Complications of head and neck radiation therapy and their management. J PROSTHET DENT 1983;49:514-22. 6. Marx RE, Johnson RP. Studies in the radiobiology of osteoradionecrosis and their clinical significance. Oral Surg Oral Med Oral Pathol 1987;64:379-90. I. Rahn AO, Matalon V, Drane JB. Prosthetic evaluation of patients who have received irradiation to the head and neck regions. J PROSTHET DENT 1958;19:174-9. 8. Dreizen S, Daley T, Drane JB. Prevention of xerostomia-related dental caries in irradiated cancer patients. J Dent Res 1977;56:99-104. 9. Khan F, Moore V, Burns D. An apparatus for the construction of irregular surface compensators for use in radiotherapy. Radiology 1968; 90:593-4.
6. Try the bolus compensatoron the patient to assure easy and accurate positioning (Fig. 5). Multisection
bolus compensator
1. Follow steps 1 and 2 for the one-sectionbolus com-
pensator (Fig. 6). 2. Trim the stone cast to the desired size of the treatment region. 3. Assessregionsof undercuts and the path of insertion
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
10. Million R, Cassisi N. Management of head and neck cancer. A multidisciulinarv aDDrOach. Philadelphia: JB Lippincott, 1984:426-7. 11. Moss WT, Cox JD. Radiation oncology-rationale, technique, results. 3rd ed. St Louis: CV Mosby Co, 1989:136-7. 12. Khan F, Moore V, Burns D. The construction of compensators for cobalt teletherapy. Radiology 1970;96:187-92. 13. Hall E, Oliver R. The use of standard isodose distributions with high energy radiation beams-the accuracy of a compensator technique in correcting for body contours. Br J Radio1 1961;34:43-52. 14. Boge R, Edland R, Matthes D. Tissue compensators for megavoltage . ^ -... radiotherapy fabricated from hollowed Styrofoam tilled with wax. Radiology 1974;111:193-8. _
“._
373
DRISCOLL,
15. Powers W, Kinzie J, Demidecki A, Bradfield J, Feldman A. A new system of field shaping for external beam radiation therapy. Radiology 1973;108:407-11, 16. Watkins D. A proposed method for making reduced wax compensators for use with high energy radiation beams. Br J Radio1 1975;48:760-2. 17. Weeks K, Fraass B, Hutchins K. Gypsum mixtures for compensator construction. Med Phys 1988$5:410-4. 18. Ellis F, Hall E, Oliver R. A compensator for variations in tissue thickness for high energy beams. Br J Radio1 1959,32:421-2. 19. Fletcher G. Textbook of radiotherapy. 3rd ed. Philadelphia:Lea & Febiger, 1980:20-4. 20. Ellis F. Accuracy in compensation for tissue heterogeneity in treatment by x-rays, supervoltage x-rays, and electron beams. Br J Radial 1960;33:404-5.
An acrylic
resin
TAYLOR,
AND
OSTROWSKI
21. Hall E, Oliver R. The use of metal compensators to correct for tissue heterogeneity in radiotherapy with high energy radiation beams. Br J Radio1 1962;35:852-5. 22. DeVita V, Hellman S, Rosenberg S. AIDS etiology, diagnosis, treatment, and prevention. 2nd ed. Philadelphia:JB Lippincott, 1988254-5.
Reprint
requests
to:
DR. CARL F. DRISCOLL C, MAXILLOFACIAI, PROSTHODONTICS USA DENTAC TRIPLER ARMY MEDICAL CENTER HONOLULU, HI 96859
core for processing
silicone
facial
prostheses
James C. Lemon, DDS,a Jack W. Martin, DDS, MS,b Juan C. Echeverri, DDS,C and Gordon E. King, DDSd The University of Texas, M.D. Anderson Cancer Center, Houston, Texas A technique is presented for making an acrylic resin core for processing silicone facial prostheses. This technique ensures a durable core that can be used to make multiple prostheses. The core resists fungal growth during storage and creates a smooth, easily cleanable internal surface for a facial prosthesis. The core also permits a controllable thickness and therefore a lighter prosthesis. (J PROSTHET DENT 1992;67:3’74-6.)
A
aAssistant Professor, Department of Dental Oncology. “Associate Professor, Department of Dental Oncology. CFellow, Department of Dental Oncology. dProfessor, Department of Dental Oncology. 10/l/29119
removable stone core, as part of a three-piece mold (Fig. l), hasoften been usedduring processingnasal prosthesesto control thickness and weight of the prostheses.Stone coresare susceptibleto abrasion and breakage. Continuous useof a stone core for multiple prosthesescan
Fig. 1. Three-piece mold with conventional stone core. Note fracture lines and repaired areasof core.
Fig. 2. Prosthesisprocessedwith stone core. Note rough internal silicone finish.
374
MARCH
1992
VOLUME
67
NUMBER
3
of
Carl F. Driscoll, DMD,* Michael A. Taylor, MS,b and John S. Ostrowski, DMDc Tripler Army Medical Center, Honolulu, Hawaii; and National Naval Dental School, Bethesda, Md. Radiation
involving irregular surfaces of facial topography often causes treatment difficulties for the radiation oncologists. The isodose curves normally used become skewed, thereby making treatment planning more complex. A simple and useful technique is presented describing the use of dental materials to make a bolus compensator to aid in radiation therapy of nonplanar surfaces. This technique will allow the radiation oncologist to treat these patients in a most efficient manner. The materials needed are readily available to the dentist and are easily handled. (J PROSTHET DENT 1992;67:370-4.)
I
n 1990, the American Cancer Institute estimated that the number of new head and neck cancer patients would grow to over 42,000 patients.’ One possible mode of treatment for these new cancer patients involves the use of ionizing beams or radiation therapy administered separately or in conjunction with surgery or chemotherapy. The dental profession has long played an active role in this treatment modality by improving and maintaining the oral health of the patient prior to, during, and following the administration of radiation treatment.2-8 Fabrication of radiation positioners and shielding devices are two examples of dental contributions to the treatment of patients undergoing radiation therapy. Another aspect of radiation therapy where dental assistance can be used is in making bolus compensators. The purpose of bolus compensators is to improve the quality of the radiation beam in treating irregular surfaces of the facial topography.g-12 Radiation beams are evaluated with respect to isodose curves that are based on measurements made in a phantom of unit density material having a flat surface perpendicular to the long axis of the beam.g, l3 When the beam enters a nonplanar surface, such as the irregular surface of the face, a skewing of the isodose curve results (Fig. l).‘, l4 This
The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army, the Department of the Navy, or the Department of Defense. BLieutenant Colonel; Chief, MaxiIlofacial Prosthodontics, U.S. Army DENTAC, Tripler Army Medical Center. bCommander; Chief, Medical Physics, National Naval Medical Center. %aptain; Chief, Maxillofacial Prosthodontics, National Naval Dental School. 10/l/26665
370
Fig. 1. Skewing of isodose curves from posed beams on irregular surfaces.
Fig. 2. Effect of bolus compensator with same beams as in Fig. 1.
MARCH1992
bilaterally
on isodose
VOLUME67
op-
curves
NUMBER3
FABRICATION
OF BOLUS
COMPENSATORS
Fig. 3. Cast. trimmed blocked out with clay.
to desired
size and undercuts
Fig.
Fig.
4. Cast and bolus compensator.
Fig.
5. Bolus compensatorin place.
phenomenonrenders the standard isodosecurves ineffective, thereby complicating treatment planning.gv12+ l4There is a needto convert irregular tissuecontours into a flat surface perpendicular to the central axis of the ionizing beam (Fig. 2)g-13to more accurately apply these isodosecurves.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
6. Cast with outline of lesion and treatment region.
The useof the boluscompensatorhaslong beenknown, but the technique of easy fabrication at a reasonablecost has not been adequately addressed. The literature is replete with suggestedbolus compensatormaterials and techniques.However, someof thesetechniquesrequire the useof sophisticatedthree-dimensionalmilling machinesor holographic image recorders that are beyond the budget and/or capacity of many radiation therapy facilities.g-21 Without these sophisticateddevices,the production of accurate bolus compensatorsbecomesvery difficult. Often, the radiation oncology personnel must attempt to make their own devices using crude techniques, with lessthan ideal results. One drawback mentioned with respect to this type of tissue boluscompensatoris the lossof the skin-sparing effect of the ionizing beam when the bolus compensator is placed immediately adjacent to the skin.g,17,2oHowever, when one is treating superficial lesions,the skin-sparing effect may not be desirablebecausethe radiation oncologist requiresthe maximum beameffect to be at the level of the skin or just below it, as in the treatment of basalcell carcinomasor Kaposi’s sarcomas.15, 22 This article describesa simple and effective technique for making boluscompensator.The boluscompensatorwill
371
DRISCOLL,
Fig. 7. First section of bolus compensator rating
TAYLOR,
AND
OSTROWSKI
made incorpo-
undercut.
Fig. 9. Sections tried on individually gether (B).
(A) and then to-
aid the radiation oncologist in the treatment of superficial lesions of the faee with irregular contours. Two patients presented illustrate the fabrication and positioning of the bolus compensator.
TECHNIQUE One-section
Fig. 8. Duplicated compensator.
cast including
first section
of bolus
bolus
compensator
1. Make a moulage of affected and adjacent tissues. 2. Have the radiation oncologist and physicist outline the desired dimensions (width, length, and depth) of the bolus compensator. 3. Trim the stone cast to the desired size of the treatment region and block out undercuts with clay (Fig. 3). 4. Box the cast using masking tape, and lubricate. 5. Pour molten wax into the boxed cast, allow to harden, and separate (Fig. 4). Adjust the height to the desired dimension. This pattern can be flasked and processed with methylmethacrylate resin if desired.
MARCH
1992
VOLUME
67
NUMBER
3
FABRICATION
OF BOLUS
COMPENSATORS
and withdrawal. Visualize the design to allow for placement as well as obliteration of the undercut. 4. Lubricate the cast and fill undercuts with wax to the desired shape (Fig. 7). This step may entail two or more sections. 5. Duplicate the cast (Fig. 8). 6. Box the duplicated cast and lubricate. 7. Flow molten wax onto the duplicate cast and allow the wax to harden. Adjust the height to the desired dimension. a. Position the individual wax sectionson the master cast to ensureproper fit. 9. Position the bolus compensatoron the patient to assure accuracy (Fig. 9). 10. Handles and interlocking sectionsmay also be required (Fig. 10). CONCLUSIONS A simpleand effective technique to aid the radiation oncologist in treating the irregular surfacesof the face of head and neck cancer patients hasbeen described.The materials are readily available and are easily handled. Further evaluation of the effectivenessof various dental materials for use as bolus compensatorsis currently being investigated.
REFERENCES
Fig. 10. A, B, and C, Handles and interlocking sections are sometimesrequired.
1. American Cancer Societv. CA 1990:40:18-21. 2. NIH consensus statement. National Institutes of Health consensus development conference statement. Oral complications of cancer therapies: diagnosis, prevention, and treatment. J Am Dent Assoc 1989; 119179-83. 3. Beumer J, Curtis TA. Radiation therapy of the head and neck tumors: oral effects and manifestations. In: Beumer J, Curtis TA, Firtell D, eds. Maxillofacial rehabilitation. St Louis: CV Mosby Co, 1979. 4. Rothwell B. Prevention and treatment of the orofacial complications of radiotherapy. J Am Dent Assoc 1987;114:316-22. 5. Engelmeier RL, King GE. Complications of head and neck radiation therapy and their management. J PROSTHET DENT 1983;49:514-22. 6. Marx RE, Johnson RP. Studies in the radiobiology of osteoradionecrosis and their clinical significance. Oral Surg Oral Med Oral Pathol 1987;64:379-90. I. Rahn AO, Matalon V, Drane JB. Prosthetic evaluation of patients who have received irradiation to the head and neck regions. J PROSTHET DENT 1958;19:174-9. 8. Dreizen S, Daley T, Drane JB. Prevention of xerostomia-related dental caries in irradiated cancer patients. J Dent Res 1977;56:99-104. 9. Khan F, Moore V, Burns D. An apparatus for the construction of irregular surface compensators for use in radiotherapy. Radiology 1968; 90:593-4.
6. Try the bolus compensatoron the patient to assure easy and accurate positioning (Fig. 5). Multisection
bolus compensator
1. Follow steps 1 and 2 for the one-sectionbolus com-
pensator (Fig. 6). 2. Trim the stone cast to the desired size of the treatment region. 3. Assessregionsof undercuts and the path of insertion
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
10. Million R, Cassisi N. Management of head and neck cancer. A multidisciulinarv aDDrOach. Philadelphia: JB Lippincott, 1984:426-7. 11. Moss WT, Cox JD. Radiation oncology-rationale, technique, results. 3rd ed. St Louis: CV Mosby Co, 1989:136-7. 12. Khan F, Moore V, Burns D. The construction of compensators for cobalt teletherapy. Radiology 1970;96:187-92. 13. Hall E, Oliver R. The use of standard isodose distributions with high energy radiation beams-the accuracy of a compensator technique in correcting for body contours. Br J Radio1 1961;34:43-52. 14. Boge R, Edland R, Matthes D. Tissue compensators for megavoltage . ^ -... radiotherapy fabricated from hollowed Styrofoam tilled with wax. Radiology 1974;111:193-8. _
“._
373
DRISCOLL,
15. Powers W, Kinzie J, Demidecki A, Bradfield J, Feldman A. A new system of field shaping for external beam radiation therapy. Radiology 1973;108:407-11, 16. Watkins D. A proposed method for making reduced wax compensators for use with high energy radiation beams. Br J Radio1 1975;48:760-2. 17. Weeks K, Fraass B, Hutchins K. Gypsum mixtures for compensator construction. Med Phys 1988$5:410-4. 18. Ellis F, Hall E, Oliver R. A compensator for variations in tissue thickness for high energy beams. Br J Radio1 1959,32:421-2. 19. Fletcher G. Textbook of radiotherapy. 3rd ed. Philadelphia:Lea & Febiger, 1980:20-4. 20. Ellis F. Accuracy in compensation for tissue heterogeneity in treatment by x-rays, supervoltage x-rays, and electron beams. Br J Radial 1960;33:404-5.
An acrylic
resin
TAYLOR,
AND
OSTROWSKI
21. Hall E, Oliver R. The use of metal compensators to correct for tissue heterogeneity in radiotherapy with high energy radiation beams. Br J Radio1 1962;35:852-5. 22. DeVita V, Hellman S, Rosenberg S. AIDS etiology, diagnosis, treatment, and prevention. 2nd ed. Philadelphia:JB Lippincott, 1988254-5.
Reprint
requests
to:
DR. CARL F. DRISCOLL C, MAXILLOFACIAI, PROSTHODONTICS USA DENTAC TRIPLER ARMY MEDICAL CENTER HONOLULU, HI 96859
core for processing
silicone
facial
prostheses
James C. Lemon, DDS,a Jack W. Martin, DDS, MS,b Juan C. Echeverri, DDS,C and Gordon E. King, DDSd The University of Texas, M.D. Anderson Cancer Center, Houston, Texas A technique is presented for making an acrylic resin core for processing silicone facial prostheses. This technique ensures a durable core that can be used to make multiple prostheses. The core resists fungal growth during storage and creates a smooth, easily cleanable internal surface for a facial prosthesis. The core also permits a controllable thickness and therefore a lighter prosthesis. (J PROSTHET DENT 1992;67:3’74-6.)
A
aAssistant Professor, Department of Dental Oncology. “Associate Professor, Department of Dental Oncology. CFellow, Department of Dental Oncology. dProfessor, Department of Dental Oncology. 10/l/29119
removable stone core, as part of a three-piece mold (Fig. l), hasoften been usedduring processingnasal prosthesesto control thickness and weight of the prostheses.Stone coresare susceptibleto abrasion and breakage. Continuous useof a stone core for multiple prosthesescan
Fig. 1. Three-piece mold with conventional stone core. Note fracture lines and repaired areasof core.
Fig. 2. Prosthesisprocessedwith stone core. Note rough internal silicone finish.
374
MARCH
1992
VOLUME
67
NUMBER
3