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. [ABSTRACT FROM AUTHOR]