Monte Carlo simulations of electron interactions with the DNA molecule: A complete set of physics models for Geant4-DNA simulation toolkit

In this study we are introducing an update of the Geant4-DNA physics constructor "option 6" including electron interactions with all constituents of the DNA molecule in addition to those already publicly available for liquid water. The new implementation is based on the interaction cross sections of electrons with the four DNA nucleobases, deoxyribose and phosphoric acid for elastic scattering, electronic excitation and ionisation in the 11 eV - 1 MeV energy range. An additional sampling method to estimate the transferred secondary electron energy produced by ionisation is also introduced and can be optionally activated instead of the classical interpolation method based on the differential cross section tables, thus eliminating the need to upload large data files. The implementation in Geant4-DNA was verified by calculating range and electronic stopping power in the various materials. Good agreement is observed with the data available in the literature, and calculations with the interpolation method and the sampling method showed less than 4% difference. No differences were observed in terms of computational cost.