Monte Carlo simulation of base damage as a function of linear energy transfer for applications in radiation biophysics

This work presents simulations of the concentration of clustered DNA damage of various complexities induced by monoenergetic electrons, protons, and alpha particles within the range of linear energy transfer (LET). Using Geant4-DNA tool, we measured the LET in liquid water and calculated the frequency of base damage around single strand breaks, double strand breaks, and complex strand breaks. The protons and the alpha particles depended greatly on LET, which affected the concentration of base damage. For alpha particles, at 206.40 keV/mu m, a high LET region was irradiated, the number of cases with more than 6 base damages was increased by about 70 times compared to the low LET region. The data indicate that high-LET radiation is likely to be much more effective in producing concentrated clusters of damage, and that having a quantitative estimate of the extent of this type of damage is important. These lesions are responsible for most of the significant cellular effects associated with ionizing radiation.