- Email: [email protected]
Clinical evaluation of 3-D treatment planning for maxillary cancer using the CT simulator
Proceedings of the 33rd Annual ASTRO Meeting
231
1077 CLINICAL EVALUATION CIF 3-D TREATMENT PLANNING FOR MAXILLARY CANCER USING THE CT SIMULATOR Kazusige Tsutsui M.D., Nagata M.D., Koji Ono M.D., Takehiro Nishidai Ph.D., Shinitirou Masunaga M.D., Kaoru Okajima M.D., Kazuhisa Fujiwara M.D., Masaji Takahashi M.D., Mitsuyuki Abe M.D.
Yasushi
Dept.
of Radiology,
P.yoto Univ.
Hospital,
Sakyo
Kyoto
606
Japan
To evaluate clinical efficacy of 3-D treatment planning for maxillary cancer Purpose: using the CT simulator. Materials and Methods: Maxillary cancer can be clearly delineated by CT and is suitable for In 1988, we developed a new 3-D treatment planning system named the CT treatment planninq. CT simulator(CT-S), and this system has been applied to maxillary cancer in 18 patients from 1988 to 1990. We compared the results with our previous planning method using X-ray based on CT films in 21 patients from 1985 till 1987. simulations Results: The average field size using CT-S ( 71.9 cm2) did not_ change from that (73.8 cm2) avoidance of scattered irradiation to the contralateral lens was before CT-S . However, patient possible and sparing of the ipsilateral lens was also occasionally possible for were near the orbital cavity. Among the 18 patients whose treatment was whose tumors planned with the CT-S, the ipsilateral lens was irradiated to more than 50% of the tumor cases (44%), to O-50% of the dose in 8118 and was spared maximum dose in 2/18 cases (ll%), completely in 8/18 cases (44%). With our previous planning system, the numbers were 8121 and II/21 (52%), respectively. In the 18 CT-S patients, the (38%), 2/21 (IO%), contralateral lens was never irradiated 'co more than 50% of the total tumor dose, was irradiated to O-50% of the dose in l/18 cases (5%), and was spared in 17118 cases (95%). In the numbers were 2/21( 10%),6/21 (29 %), and 13/21 (61%), the previous 21 patients, CT-S was especially useful for establishing oblique fields in 8/18 cases respectively. (44%) when the contralateral lens was spared using lead blocks. Perpendicular pairs were previously used in 16/21 (76%) cases when irradiation to contralateral lens could not be avoided. The following 3-D images were useful using CT-S. Beam's eye view(l) was especially useful within the tumor, 3-D for establishing blocks over lens. To assure dose homogeneity reconstructed images with dose distribution curves(2) and Dose Volume Spectrum(3) were useful. Reconstructed target outline over sccanograms(4) was useful for target orientation and Simulation image(5), digittaly reconstructed radiograph was useful for verification. Conclusions: CT-S was especially useful for planning maxillary cancer when we want to spare irradiation to lens using oblique portals.
1078 CONFORMAL RADIATION THERAPY OF PANCREATIC CARCINOMA M.C.Schell,Ph.D., S.Cheng, M.D., M.Tefft,M.D., R.Fine,M.D., and P.D.Higgins,Ph.D. Radiation Therapy, Cleveland Clinic Foundation, Cleveland, OH Purpose: The purpose is to increase tumor dose by refinement of external beam treatment techniques with conformal radiotherapy and dose volume histogram (DVH) analysis of dose delivery. Carcinoma of the pancreas accounts for ten percent of all fatal abdominal malignancies and is a disease with dismal five year survival (approximately 10%). Definitive doses with external beam radiation therapy for pancreatic lesions are limited by the radiosensitivity of the neighboring critical organs; spinal cord, kidneys, small bowel, stomach, and liver. Consequently, efforts to increase the tumor dose with various techniques (precision high dose therapy, I-125 implants, etc.) have been reported. Materials & Methods: We present an analysis of the standard four-field and three-field treatment techniques with 3-D treatment planning. Dose volume histograms of the tumor and vital structures are used to evaluate the treatment plans. These treatment geometries are then modified to nonstandard gantry and table angles. The beams eye view is employed to conform the dose profile to the tumor projection. DVH analysis is used to evaluate and compare the nonstandard beam geometries with the conventional techniques. The DVH analysis is used to quantify the normal tissue dose delivery as a function of opposed fields, coplanar and noncoplanar configurations. Results & Conclusion: The use of DVH analysis has enabled the development of a treatment approach which reduces the dose to the surrounding normal tissues and provides for a 15-20% increased tumor dose.
231
1077 CLINICAL EVALUATION CIF 3-D TREATMENT PLANNING FOR MAXILLARY CANCER USING THE CT SIMULATOR Kazusige Tsutsui M.D., Nagata M.D., Koji Ono M.D., Takehiro Nishidai Ph.D., Shinitirou Masunaga M.D., Kaoru Okajima M.D., Kazuhisa Fujiwara M.D., Masaji Takahashi M.D., Mitsuyuki Abe M.D.
Yasushi
Dept.
of Radiology,
P.yoto Univ.
Hospital,
Sakyo
Kyoto
606
Japan
To evaluate clinical efficacy of 3-D treatment planning for maxillary cancer Purpose: using the CT simulator. Materials and Methods: Maxillary cancer can be clearly delineated by CT and is suitable for In 1988, we developed a new 3-D treatment planning system named the CT treatment planninq. CT simulator(CT-S), and this system has been applied to maxillary cancer in 18 patients from 1988 to 1990. We compared the results with our previous planning method using X-ray based on CT films in 21 patients from 1985 till 1987. simulations Results: The average field size using CT-S ( 71.9 cm2) did not_ change from that (73.8 cm2) avoidance of scattered irradiation to the contralateral lens was before CT-S . However, patient possible and sparing of the ipsilateral lens was also occasionally possible for were near the orbital cavity. Among the 18 patients whose treatment was whose tumors planned with the CT-S, the ipsilateral lens was irradiated to more than 50% of the tumor cases (44%), to O-50% of the dose in 8118 and was spared maximum dose in 2/18 cases (ll%), completely in 8/18 cases (44%). With our previous planning system, the numbers were 8121 and II/21 (52%), respectively. In the 18 CT-S patients, the (38%), 2/21 (IO%), contralateral lens was never irradiated 'co more than 50% of the total tumor dose, was irradiated to O-50% of the dose in l/18 cases (5%), and was spared in 17118 cases (95%). In the numbers were 2/21( 10%),6/21 (29 %), and 13/21 (61%), the previous 21 patients, CT-S was especially useful for establishing oblique fields in 8/18 cases respectively. (44%) when the contralateral lens was spared using lead blocks. Perpendicular pairs were previously used in 16/21 (76%) cases when irradiation to contralateral lens could not be avoided. The following 3-D images were useful using CT-S. Beam's eye view(l) was especially useful within the tumor, 3-D for establishing blocks over lens. To assure dose homogeneity reconstructed images with dose distribution curves(2) and Dose Volume Spectrum(3) were useful. Reconstructed target outline over sccanograms(4) was useful for target orientation and Simulation image(5), digittaly reconstructed radiograph was useful for verification. Conclusions: CT-S was especially useful for planning maxillary cancer when we want to spare irradiation to lens using oblique portals.
1078 CONFORMAL RADIATION THERAPY OF PANCREATIC CARCINOMA M.C.Schell,Ph.D., S.Cheng, M.D., M.Tefft,M.D., R.Fine,M.D., and P.D.Higgins,Ph.D. Radiation Therapy, Cleveland Clinic Foundation, Cleveland, OH Purpose: The purpose is to increase tumor dose by refinement of external beam treatment techniques with conformal radiotherapy and dose volume histogram (DVH) analysis of dose delivery. Carcinoma of the pancreas accounts for ten percent of all fatal abdominal malignancies and is a disease with dismal five year survival (approximately 10%). Definitive doses with external beam radiation therapy for pancreatic lesions are limited by the radiosensitivity of the neighboring critical organs; spinal cord, kidneys, small bowel, stomach, and liver. Consequently, efforts to increase the tumor dose with various techniques (precision high dose therapy, I-125 implants, etc.) have been reported. Materials & Methods: We present an analysis of the standard four-field and three-field treatment techniques with 3-D treatment planning. Dose volume histograms of the tumor and vital structures are used to evaluate the treatment plans. These treatment geometries are then modified to nonstandard gantry and table angles. The beams eye view is employed to conform the dose profile to the tumor projection. DVH analysis is used to evaluate and compare the nonstandard beam geometries with the conventional techniques. The DVH analysis is used to quantify the normal tissue dose delivery as a function of opposed fields, coplanar and noncoplanar configurations. Results & Conclusion: The use of DVH analysis has enabled the development of a treatment approach which reduces the dose to the surrounding normal tissues and provides for a 15-20% increased tumor dose.