Abstract
Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Livermore data is used to calculate electromagnetic interaction of primary and secondary charged particles. We validate the models using experimental data of 200 MeV/u and 400 MeV/u carbon ions, interacting with tissue equivalent materials of water. The model can well describe the depth-dose distributions in water and the doses measured for secondary fragments of certain charge and certain mass number. The secondary beam fragments produced by 200 MeV/u and 400 MeV/u 12C6+ ions in water are investigated using the model. When the primary nuclei are in water, several neutron production mechanisms are involved. The light charged particles (p, d, t, 3He and 4He) and fast neutrons contribute to the dose tail behind the Bragg peak. The 11C fragments which may be the most suitable nuclei for monitoring the energy deposition in carbon-ion therapy are also discussed.