Energy deposition and relative frequency of hits of cylindrical nanovolume in medium irradiated by ions: Monte Carlo simulation of tracks structure.

Radiation track structure simulations have been used for many years to study the DNA damage caused by heavy ions. These studies are highly relevant for treatment planning of heavy ion radiotherapy and space radiation risk assessment. Measurements of the frequency of delta-rays hits, mean specific energy per target hits and per ion, and the frequency of dose distribution in a cylindrical target volume placed at various radial distances from 4He 2+, 12C 6+ and 16O 8+ tracks have been performed by Schmollack et al. (in Radiat Res 153:469-478, 2000). In the present work, Monte Carlo simulation of radiation tracks has been performed with the RITRACKS and the RETRACKS codes along with a target volume to simulate the experiment of Schmollack et al. The results of these simulations are compared to those of previous deterministic models of the radial dependence of the mean specific energy. Our Monte Carlo simulations are consistent with the experimental data both in the core and in the penumbra of the beam, and are shown to provide a better description of the experimental data than deterministic codes.