Investigate the radiation-induced damage on an atomistic DNA model by using Geant4-DNA toolkit

The study of biologic effects of ionizing radiation is important in many fields. In this work, we build a DNA model from the atomic level and study the DNA damage caused by low energy electrons, protons and alpha particles with Geant4-DNA code. Damage yields, including total strand break yields (SBY), single strand break yields (SSBY), double strand break yields (DSBY) and SSB+ yields (SSB + Y), are calculated for each beam. According to the simulation results, direct strand break yields are almost independent of the projectile features and indirect strand break yields decrease with the LET for more radicals reacting with each other. Simple damage yields, like SSBY, decrease with the LET but the total yields of complex damage increase with the LET for the clustering of energy deposition events and radical productions. In the study, different physics and chemistry constructors are used to simulate the direct and indirect damages caused by electrons. Simulation results show that the direct SBY simulated by the physics option4 constructor are, on average, 6.7% and 30.9% higher than the option6 and option2 constructors, respectively, because of the different cross sections implemented in these models. The indirect SBY simulated by chemistry option1 constructor are about 18.3% less than that of the chemistry default constructor due to the different chemical parameters used in these constructors. A comparison with experiment data and other simulation works is also given. The trends of different works are in consistent with each other and the DSBY of protons simulated in this work agree well with the experiment data.