Validation of nuclear reaction models in Geant4 for the purpose of carbon ion radiotherapy

High energetic carbon beams are currently used for radiotherapy at several facilities in the world. Geant4 Monte Carlo simulation tool-kit has been introduced for dose calculation in carbon ion radiotherapy. Some models to treat nucleus-nucleus interactions are implemented in Geant4 to simulate nuclear fragmentation. Detailed physics validation for fragmentation models in Geant4 is indispensable in order to improve its dosimetric performance and establish its reliability. We validate fragmentation models in Geant4 using experimental data of 200 - 400 MeV/nucleon ¹²C ions, interacting with tissue equivalent materials of water and polycarbonate obtained by NIRS-HIMAC P152 experiment. This study is of importance both for persons to develop or improve the fragmentation models and for those to perform the dose calculation in carbon ion therapy using Geant4.