Dose evaluation using Monte Carlo calculation with whole-body patient CT data for retrospective dose analysis in carbon ion radiotherapy

Hirai, Yuta*; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Shinsho, Kiyomitsu*

no journal, , 

Irradiation of normal tissues cannot be completely avoided in radiotherapy, and there is a known risk of secondary cancer development due to radiation exposure in the prognosis. Although it has been reported that the incidence of secondary cancer is predominantly lower in carbon-ion radiotherapy for localized prostate cancer than in photon therapy, dose assessment only around the treatment site by conventional treatment planning systems is not sufficient to better understand the relationship between secondary cancer incidence and radiation dose. Therefore, the Japan Atomic Energy Agency and the Quantum Science and Technology Agency have developed RT-PHITS for CIRT, a system that can calculate and evaluate a wide range of dose distribution during carbon-ion radiotherapy for patients using the Monte Carlo method. In this study, using the developed system and whole-patient CT data provided by The Cancer Imaging Archive, we created treatment plans to treat the prostate cancer on the patient and performed detailed dose evaluation for low-dose areas far from the treatment site. We confirmed the usefulness of this system for retrospective dose analysis of carbon-ion radiotherapy.