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Pelvic Proton Radiotherapy for High-risk Prostate Cancer
I. J. Radiation Oncology d Biology d Physics
S326
Volume 72, Number 1, Supplement, 2008
Only patients with intermediate risk features appeared to benefit with the addition of hormones with 3 yr/5 yr biochemical control rates of 95.9%/84.7% without hormones versus 98.1%/98.1% with hormonal therapy. Grade 3 toxicities were observed as follows: 2.5% acute GU, 5.9% chronic GU, .7% acute GI, 0.7% chronic GI. There were no Grade 4 or 5 toxicities observed. Conclusions: Prostate IMRT is a well tolerated treatment option that with longer term follow-up continues to demonstrate excellent biochemical control rates. Chronic toxicities were very low. Author Disclosure: S.A. Vora, None; W.W. Wong, None; S.E. Schild, None; G.A. Ezzell, None.
2350
Pelvic Proton Radiotherapy for High-risk Prostate Cancer 1
B. S. Chera , C. Vargas2, S. Flampouri3, C. G. Morris1, D. Yeung3, K. Olivier1, S. Duvvuri3, Z. Li3, N. P. Mendenhall3 1 3
University of Florida Shands Cancer Center, Gainesville, FL, 2Boca Radiation Oncology Associates, Boca Raton, FL, University of Florida Proton Therapy Institute, Jacksonville, FL
Purpose/Objective(s): To compare dose distribution to volumes of targeted tissues (prostate, seminal vesicles, and pelvic regional nodes at high risk for harboring microscopic disease) and non-targeted tissues (rectum, bladder, small bowel, femurs, and pelvis) in the pelvis with intensity-modulated radiotherapy (IMRT) and forward-planned, double-scattered three-dimensional proton radiotherapy (3DCPRT). Materials/Methods: An IMRT followed by a prostate 3DCPRT boost (IMRT/3DCPRT), and 3DCPRT plans were created for 5 high-risk prostate cancer patients treated in our Phase II high-risk prostate proton protocol (n = 15 plans). Seventy-eight GE/Gy was prescribed to the prostate and proximal seminal vesicles and 46 GE/Gy was prescribed to the pelvic nodes. Various dosimetric endpoints between the three modalities were compared. Results: Target coverage of the prostate planning target volume (PTV) and nodal PTV was adequate for all three plans. The 3DCPRT plans, when compared to the IMRT and IMRT/3DCPRT plans, reduced the mean dose to the rectum, rectal wall, bladder, bladder wall, small bowel, and pelvis (p\0.05). When comparing IMRT to IMRT/3DCPRT plans, the IMRT/3DCPRT plans (p\ 0.05) reduced the mean dose to all non-target tissues except the small bowel, pelvis, and femurs. The relative benefit of 3DCPRT therapy at reducing the rectum and rectal wall V5 to V70 GE/Gy ranged from 9% to 62% (p \ 0.05). For the bladder and bladder wall, the relative benefit for V5 to V45 GE/Gy was 24% to 46% (p \ 0.05). The relative benefit for reducing the volume of small bowel irradiated from 5 to 30 GE/Gy in the 3DCPRT ranged from 56% to 62%. 3DCPRT was better than IMRT or IMRT/3DCPRT at sparing non-target tissues. 3DCPRT did not exhibit the typical low-dose ‘‘bath’’ of radiation to the pelvis seen with IMRT. Femoral head doses were higher with 3DCPRT. Conclusions: 3DCPRT significantly reduced the dose to normal tissues in the pelvis while maintaining adequate coverage of the prostate, proximal seminal vesicles, and pelvic lymph nodes when compared to IMRT or IMRT/3DCPRT. When treating the prostate, seminal vesicles, and pelvic lymph nodes in prostate cancer, proton therapy may improve the therapeutic ratio beyond what is possible with IMRT. Author Disclosure: B.S. Chera, None; C. Vargas, None; S. Flampouri, None; C.G. Morris, None; D. Yeung, None; K. Olivier, None; S. Duvvuri, None; Z. Li, None; N.P. Mendenhall, None.
2351
Target Positioning Accuracy of a Novel Technology for Target Localization in Radiation Therapy 1
D. Schifter , T. Djemil2, B. Corn1, A. Mahadevan2, R. Lichtman1, R. Macklis2 1
Tel Aviv Medical Center, Tel Aviv, Israel, 2Cleveland Clinic Foundation, Cleveland, OH
Purpose/Objective(s): Position accuracy has long been an essential and challenging issue in radiation oncology. With more localized treatment modalities becoming more popular, like IMRT, Body Radiosurgery, etc., the demand for accurate and quick localization has increased and many image guided systems have been introduced to the market (i.e., Cone Beam CT, Orthogonal Xrays, Optical tracking, Ultrasound). All of them require substantial pre-treatment setup time and sometimes physician analysis. A need for a fast, accurate, and objective target localization system has been recognized. This is extremely important for targets which are not attached to bones (like prostate) and one cannot rely on bony anatomy for localization. Materials/Methods: The system used is a set of detectors attached to a linac gantry and a radioactive fiducial seed implanted in the target. The active isotope in the seed is a 50 mCi 192Ir. The detector system does not interfere with the gantry and collimator movements and the reduction in clearance is about the same as for any external MMLC system (about 8 cm). The target was localized with the system and then a cone beam CT was performed to check the localization accuracy. Localization and accuracy measurement was performed six times. The test was performed using a tissue equivalent body phantom. Results: The mean positioning accuracy of the system was 0.3 mm, with std. of 0.16 mm. The localization was real time and the entire process took less then one minute (including repositioning, not including the CBCT which will not be a part of the clinical system). Conclusions: The radioactive tracking system is a fast, accurate and objective system which is appropriate for real time localization and positioning in radiation therapy. It has great potential utility for rapid and accurate beam positioning and for localization of both targets and critical normal tissues. Author Disclosure: D. Schifter, None; T. Djemil, None; B. Corn, None; A. Mahadevan, None; R. Lichtman, None; R. Macklis, None.
2352
Analysis of the Pro-qura Database: Implant Quality, Brachytherapist Experience and Rectal Dose Parameters
C. Louiselle1, G. S. Merrick2, J. Sylvester3, P. Grimm3, S. Eulau3, M. Waheed2, Z. A. Allen2, W. M. Butler2 1
University of Washington, Seattle, WA, 2Schiffler Cancer Center, Wheeling, WV, 3Seattle Prostate Institute, Seattle, WA
Purpose/Objective(s): Following permanent prostate brachytherapy, rectal dose (R100) has correlated with rectal morbidity including bleeding. This study evaluated the influence of Pro-Qura feedback on rectal dosimetry in community-based brachytherapy programs.
S326
Volume 72, Number 1, Supplement, 2008
Only patients with intermediate risk features appeared to benefit with the addition of hormones with 3 yr/5 yr biochemical control rates of 95.9%/84.7% without hormones versus 98.1%/98.1% with hormonal therapy. Grade 3 toxicities were observed as follows: 2.5% acute GU, 5.9% chronic GU, .7% acute GI, 0.7% chronic GI. There were no Grade 4 or 5 toxicities observed. Conclusions: Prostate IMRT is a well tolerated treatment option that with longer term follow-up continues to demonstrate excellent biochemical control rates. Chronic toxicities were very low. Author Disclosure: S.A. Vora, None; W.W. Wong, None; S.E. Schild, None; G.A. Ezzell, None.
2350
Pelvic Proton Radiotherapy for High-risk Prostate Cancer 1
B. S. Chera , C. Vargas2, S. Flampouri3, C. G. Morris1, D. Yeung3, K. Olivier1, S. Duvvuri3, Z. Li3, N. P. Mendenhall3 1 3
University of Florida Shands Cancer Center, Gainesville, FL, 2Boca Radiation Oncology Associates, Boca Raton, FL, University of Florida Proton Therapy Institute, Jacksonville, FL
Purpose/Objective(s): To compare dose distribution to volumes of targeted tissues (prostate, seminal vesicles, and pelvic regional nodes at high risk for harboring microscopic disease) and non-targeted tissues (rectum, bladder, small bowel, femurs, and pelvis) in the pelvis with intensity-modulated radiotherapy (IMRT) and forward-planned, double-scattered three-dimensional proton radiotherapy (3DCPRT). Materials/Methods: An IMRT followed by a prostate 3DCPRT boost (IMRT/3DCPRT), and 3DCPRT plans were created for 5 high-risk prostate cancer patients treated in our Phase II high-risk prostate proton protocol (n = 15 plans). Seventy-eight GE/Gy was prescribed to the prostate and proximal seminal vesicles and 46 GE/Gy was prescribed to the pelvic nodes. Various dosimetric endpoints between the three modalities were compared. Results: Target coverage of the prostate planning target volume (PTV) and nodal PTV was adequate for all three plans. The 3DCPRT plans, when compared to the IMRT and IMRT/3DCPRT plans, reduced the mean dose to the rectum, rectal wall, bladder, bladder wall, small bowel, and pelvis (p\0.05). When comparing IMRT to IMRT/3DCPRT plans, the IMRT/3DCPRT plans (p\ 0.05) reduced the mean dose to all non-target tissues except the small bowel, pelvis, and femurs. The relative benefit of 3DCPRT therapy at reducing the rectum and rectal wall V5 to V70 GE/Gy ranged from 9% to 62% (p \ 0.05). For the bladder and bladder wall, the relative benefit for V5 to V45 GE/Gy was 24% to 46% (p \ 0.05). The relative benefit for reducing the volume of small bowel irradiated from 5 to 30 GE/Gy in the 3DCPRT ranged from 56% to 62%. 3DCPRT was better than IMRT or IMRT/3DCPRT at sparing non-target tissues. 3DCPRT did not exhibit the typical low-dose ‘‘bath’’ of radiation to the pelvis seen with IMRT. Femoral head doses were higher with 3DCPRT. Conclusions: 3DCPRT significantly reduced the dose to normal tissues in the pelvis while maintaining adequate coverage of the prostate, proximal seminal vesicles, and pelvic lymph nodes when compared to IMRT or IMRT/3DCPRT. When treating the prostate, seminal vesicles, and pelvic lymph nodes in prostate cancer, proton therapy may improve the therapeutic ratio beyond what is possible with IMRT. Author Disclosure: B.S. Chera, None; C. Vargas, None; S. Flampouri, None; C.G. Morris, None; D. Yeung, None; K. Olivier, None; S. Duvvuri, None; Z. Li, None; N.P. Mendenhall, None.
2351
Target Positioning Accuracy of a Novel Technology for Target Localization in Radiation Therapy 1
D. Schifter , T. Djemil2, B. Corn1, A. Mahadevan2, R. Lichtman1, R. Macklis2 1
Tel Aviv Medical Center, Tel Aviv, Israel, 2Cleveland Clinic Foundation, Cleveland, OH
Purpose/Objective(s): Position accuracy has long been an essential and challenging issue in radiation oncology. With more localized treatment modalities becoming more popular, like IMRT, Body Radiosurgery, etc., the demand for accurate and quick localization has increased and many image guided systems have been introduced to the market (i.e., Cone Beam CT, Orthogonal Xrays, Optical tracking, Ultrasound). All of them require substantial pre-treatment setup time and sometimes physician analysis. A need for a fast, accurate, and objective target localization system has been recognized. This is extremely important for targets which are not attached to bones (like prostate) and one cannot rely on bony anatomy for localization. Materials/Methods: The system used is a set of detectors attached to a linac gantry and a radioactive fiducial seed implanted in the target. The active isotope in the seed is a 50 mCi 192Ir. The detector system does not interfere with the gantry and collimator movements and the reduction in clearance is about the same as for any external MMLC system (about 8 cm). The target was localized with the system and then a cone beam CT was performed to check the localization accuracy. Localization and accuracy measurement was performed six times. The test was performed using a tissue equivalent body phantom. Results: The mean positioning accuracy of the system was 0.3 mm, with std. of 0.16 mm. The localization was real time and the entire process took less then one minute (including repositioning, not including the CBCT which will not be a part of the clinical system). Conclusions: The radioactive tracking system is a fast, accurate and objective system which is appropriate for real time localization and positioning in radiation therapy. It has great potential utility for rapid and accurate beam positioning and for localization of both targets and critical normal tissues. Author Disclosure: D. Schifter, None; T. Djemil, None; B. Corn, None; A. Mahadevan, None; R. Lichtman, None; R. Macklis, None.
2352
Analysis of the Pro-qura Database: Implant Quality, Brachytherapist Experience and Rectal Dose Parameters
C. Louiselle1, G. S. Merrick2, J. Sylvester3, P. Grimm3, S. Eulau3, M. Waheed2, Z. A. Allen2, W. M. Butler2 1
University of Washington, Seattle, WA, 2Schiffler Cancer Center, Wheeling, WV, 3Seattle Prostate Institute, Seattle, WA
Purpose/Objective(s): Following permanent prostate brachytherapy, rectal dose (R100) has correlated with rectal morbidity including bleeding. This study evaluated the influence of Pro-Qura feedback on rectal dosimetry in community-based brachytherapy programs.