Impact of anatomical changes on radiation absorbed dose of prostate and bladder in a potential scenario of magnetic resonance imaging (MRI)-guided carbon-ion radiotherapy (MRgCT) of prostate cancer

Abstract

In this study, the impact of anatomical changes on radiation dose variations of the prostate and bladder (as an organ at risk) was assessed for a potential scenario of magnetic resonance imaging-guided carbon-ion radiotherapy (MRgCT) of prostate cancer. To achieve this goal, carbon-ion beams perpendicular to a pelvis phantom affected by 1.5 T perpendicular magnetic field were simulated using the FLUKA code. Prostate diameter change from 6 to 1 cm leads to a prostate dose reduction of 88%. Bladder diameter change from 10 to 5 cm leads to a reduction of 92% in bladder dose. The set-up error of 5 mm leads to a decrease of 5% in the prostate dose. Rectum diameter change from 5 to 3 cm leads to reductions of 20% and 26% in prostate and bladder dose, respectively. In conclusion, anatomical changes impact on dose variations in MRgCT of prostate cancer.