OBJECTIVE: We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer. METHODS: 68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional-three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes. RESULTS: Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D95)-PTV1 was >98% of the prescribed dose. CONCLUSION: Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels. ADVANCES IN KNOWLEDGE: Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.
OBJECTIVE: We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer. METHODS: 68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional-three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes. RESULTS: Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D95)-PTV1 was >98% of the prescribed dose. CONCLUSION: Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels. ADVANCES IN KNOWLEDGE: Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.
Authors: Heinz Deutschmann; Gerhard Kametriser; Philipp Steininger; Philipp Scherer; Helmut Schöller; Christoph Gaisberger; Michaela Mooslechner; Bernhard Mitterlechner; Harald Weichenberger; Gert Fastner; Karl Wurstbauer; Stephan Jeschke; Rosemarie Forstner; Felix Sedlmayer Journal: Int J Radiat Oncol Biol Phys Date: 2011-12-30 Impact factor: 7.038
Authors: Piet Ost; Gert De Meerleer; Werner De Gersem; Aline Impens; Wilfried De Neve Journal: Int J Radiat Oncol Biol Phys Date: 2010-04-06 Impact factor: 7.038
Authors: Michel J Ghilezan; David A Jaffray; Jeffrey H Siewerdsen; Marcel Van Herk; Anil Shetty; Michael B Sharpe; Syed Zafar Jafri; Frank A Vicini; Richard C Matter; Donald S Brabbins; Alvaro A Martinez Journal: Int J Radiat Oncol Biol Phys Date: 2005-06-01 Impact factor: 7.038
Authors: Paul J Keall; Gig S Mageras; James M Balter; Richard S Emery; Kenneth M Forster; Steve B Jiang; Jeffrey M Kapatoes; Daniel A Low; Martin J Murphy; Brad R Murray; Chester R Ramsey; Marcel B Van Herk; S Sastry Vedam; John W Wong; Ellen Yorke Journal: Med Phys Date: 2006-10 Impact factor: 4.071