Electron transport in DNA bases: An extension of the Geant4-DNA Monte Carlo toolkit

The Geant4-DNA Monte Carlo toolkit is extended to include electron interactions with the four DNA bases using cross sections implemented in Geant-DNA CPA100 models. Electron cross sections for elastic scattering, ionisation, and excitation are calculated in the four DNA bases (adenine, thymine, guanine and cytosine) with relativistic energy range. These are implemented within the “option6” physics constructor to extend its capability of tracking electrons in DNA material in addition to liquid water. Differential and integrated cross sections calculations are in good agreement with the literature for all DNA bases. Stopping power, range and inelastic mean free path calculations in the four bases agree well with other studies, especially for high energy electrons with some deviations at low energies. Differences from water simulations emphasize the need to include DNA bases cross sections in track structure codes for better estimation of radiation effects on biological material.