Abstract ID: 90 Accounting for radiation-induced indirect damage on DNA with the GEANT4 code

• Published in: Physica medica Vol. 42; p. 19
• Main Authors: de la Fuente Rosales, Liset, Bernal Rodriguez, Mario A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2017
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2017.09.048

The use of Monte Carlo (MC) simulations remains a powerful tool to study biological effects induced by ionizing radiations on living beings. Several MC codes, with different level of complexity, are commonly used in research fields such as nanodosimetry, radiotherapy, radiation protection, and space radiation. This work performed an upgrade of an existing model developed by Bernal et al. [1] for radiobiological purposes, for accounting for the indirect DNA damage produced by ionizing particles. The Geant4-DNA simulation toolkit was used to simulate physical, pre-chemical and chemical stages of the early DNA damage induced by protons. Liquid water was used as the medium for simulations. Two phase-space files were generated, one containing energy deposition events inside the region of interest (ROI), and another one with the position of chemical species produced by water radiolysis from 0.1ps up to 1ns. The information contained in both files was superposed on a genetic material model with atomic-resolution,consisting of several copies of 30-nm chromatin fibers. The B-DNA configuration was used. This work focused on the indirect damage produced by the hydroxyl radical (OH.) at the deoxy-ribose sugar sites, normally trough hydrogen abstraction. Corresponding damage yields were determined. The approach followed to account for indirect damage in DNA was the same used by other radiobiological codes [2,3]. The critical parameter considered here was the reaction radius, which was calculated from the Smoluchowski’s diffusion equation. Single, double, and total strand break yields produced by direct, indirect, and mixed mechanisms are reported.