A simulation-based study on water radiolysis species for 1H+, 4He2+, and 12C6+ ion beams with multiple ionization using Geant4-DNA

Monte Carlo track structure simulation is a powerful method for estimating damage induced by water radiolysis products for cell killing. To investigate the influence of multiple ionization for the formation of water radiolysis products under 1H+, 4He2+, and 12C6+ ion beams, a Monte Carlo simulation based on Geant4-DNA was carried out. The G-value of H2O2 increased monotonically with increasing linear energy transfer up to 200 eV/nm. Above 200 eV/nm, the G-value of H2O2 began dropping, but only when the influence of multiple ionization was considered. This trend is in good agreement with the experimental results. Furthermore, we successfully reproduce the experimental results of G-values of HO2• + O2•−. The role of the multiple ionization in the production of H2O2, HO2•, O2•−, and O2 is also discussed