Secondary Neutron Dose in Carbon-ion Radiotherapy: Investigations in QST–NIRS

Background The National Institutes for Quantum and Radiological Science Technology–National Institute of Sciences (QST–NIRS) has continuously investigated the undesired radiation exposure in ion beam radiotherapy mainly carbon-ion (CIRT). This review introduces our investigations on secondary neutron dose CIRT with broad scanning methods. Materials Methods ambient equivalents are evaluated based rem meter (WENDI-II) measurements. out-of-field organ doses assuming prostate cancer pediatric brain tumor treatments also through Monte Carlo simulation. evaluation includes contributions from neutrons charged particles. Results Discussion measurements at a 90° angle to axis method show that per treatment is lower than proton (PRT). For energy technique, PRT. Moreover, decreased distance target less bound intensity-modulated (IMRT) shown AAPM TG-158 (American Association Physicists Medicine Task Group). Conclusion important viewpoint risk after radiotherapy. Secondary major source CIRT, especially distant area volume. However, level similar or PRT IMRT, even if all species included evaluation. Keywords: Carbon-ion Radiotherapy, Neutron, Out-of-Field Dose, WENDI-II, PHITS