Monte Carlo simulation for calculation of fragments produced by 400Â MeV/u carbon ion beam in water

Monte Carlo simulation was an important approach to obtain accurate characteristics of radiotherapy. In this work, a 400 MeV/u carbon ion beam incident on water phantom was simulated with Gate/Geant4 tools. The authors obtained the dose distributions of H, He, Li, Be, B, C and their isotopes in water phantom, and drew a conclusion that the dose of 11C was the main reason of causing the embossment of total dose curve around 252 mm depth. The authors also studied detailedly the dose contribution distributions, yield distributions and average energy distributions of all kinds of fragments. The information of four distributions was very meaningful for understanding the effect of fragments in carbon ion beam radiotherapy. The method of this simulation was easy to extend. For example, for obtaining a special result, we may change the particle energy, particle type, target material, target geometry, physics process, detector, etc.