Investigation of direct DNA damage induced by electrons and protons: a Monte Carlo simulation study

Understanding the mechanisms of ionizing radiation-induced DNA damage at the nanometer scale is crucial for radiobiology. This study investigates DNA single- and double-strand break (SSB and DSB) induction by low-energy electrons, in comparison with incident protons. A cylindrical model of a B-DNA segment was developed, and the GATE Monte Carlo (MC) toolkit (with Geant4-DNA) was used to simulate spatially resolved energy-deposition events from electrons (50 eV to 100 keV) and 2 MeV protons. From these energy-deposition patterns, SSB and DSB yields were calculated as a function of particle type and energy. The results show a strong dependence of SSB and DSB yields on electron energy, with clear variations in damage efficiency across the investigated spectrum. The comparison with protons highlights differences in strand-break induction between electrons and protons. The predicted SSB and DSB yields are overall consistent with published experimental data and previous simulation studies within a factor of 1.5–2. These findings support the use of GATE/Geant4-DNA for nanodosimetric estimation of direct DNA strand-break yields and provide useful data on the direct contribution of secondary electrons to biological damage.