Speaker
Description
A multiscale approach was developed for the first time and used to assess the early DNA radiation damage due to galactic cosmic ray (GCR) protons and the resulting backscattered lunar radiation (BLR) on the surface of the Moon using Geant4. Male and female astronauts were modelled using the ICRP145 tetrahedral mesh phantoms. GCR protons were modelled incident on the Moon surface with an isotropic angular distribution and BLR modelled using a novel biasing technique. A hybrid physics list was developed which combined Geant4 electromagnetic condensed history physics models with Geant4-DNA track structure models to be able to model the interactions of the GCR at sub-cellular level, covering an energy range from few eV up to 100 GeV. Hadronic interactions and the modelling of induced radiochemical species were also included. The early DNA damage was assessed using the Geant4-DNA molecularDNA example. It was observed that BLR contributed to around 20% of single strand breaks and up to 45% of double strand breaks. Indirect damage due to induced hydroxyl radicals constituted most of the damage. As such, the backscattered radiation component must be considered for a full understanding of the biological impact of space radiation. In addition, more DNA damage was observed in the pancreas, spleen and ovaries in comparison to other organs modelled such as the brain, breast tissues and spinal spongiosa.
