Shirin Rahmanian | Searcharxiv

arXiv2024

Comparison of Geant4-DNA and RITRACKS/RITCARD: microdosimetry, nanodosimetry and DNA break predictions

This work aims at investigating the impact of DNA geometry, compaction and calculation chain on DNA break and chromosome aberration predictions for high charge and energy (HZE) ions, using the Monte Carlo codes Geant4-DNA, RITRACKS and RITCARD. To ensure consistency of ion transport of both codes, we first compared microdosimetry and nanodosimetry spectra for different ions of interest in hadrontherapy and space research. The Rudd model was used for the transport of ions in both models. Developments were made in Geant4 (v11.2) to include periodic boundary conditions (PBC) to account for electron equilibrium in small targets. Excellent agreements were found for both microdosimetric and nanodosimetric spectra for all ion types, with and without PBC. Some discrepancies remain for low-energy deposition events, likely due to differences in electron interaction models. The latest results obtained using the newly available Geant4 example ``dsbandrepair'' will be presented and compared to DNA break predictions obtained with RITCARD.

physics.med-ph↗

arXiv2017

Measurement of fluence, LET, and dose in a carbon ion spread-out Bragg-peak using fluorescent nuclear track detectors and an automated reader

For the assessment of radiation effects of clinical ion-beams, dosimetry has to be complemented by information on particle-energy distribution or related quantities. Fluorescence nuclear track detectors made from C,Mg-doped alumina single crystals allow for the quantification of ion track density and energy loss on a single-track basis. In this study, their feasibility and accuracy to quantify fluence, linear-energy-transfer (LET) distributions, and eventually dose for a spread-out carbon ion Bragg peak was investigated. We found that the primary ions track densities agreed well with the reference data, but the determination of the individual detector sensitivity represented a major source of uncertainty in LET (and dose) assessment. While low-LET fragments in the beam are not contributing to this dose significantly, their number of was largely underestimated by approximately a factor three. The effect was most pronounced for protons where the measured fluence deviates at least an order of magnitude. We conclude that this is mainly caused by the wide angular distribution of protons in a carbon beam. The use of a dedicated FNTD reader device and semi-automated workflow improved outcome due to the considerably larger amount of data available as compared to a state-of-the-art multi-purpose confocal laser scanning microscope.

physics.med-ph↗