Geant4-DNA modeling of nanodosimetric quantities in the Jet Counter for alpha particles

Abstract

The purpose of this work was to validate the calculation accuracy of nanodosimetric quantities in Geant4-DNA track structure simulation code. We implemented the Jet Counter (JC) nanodosimeter geometry in the simulation platform and quantified the impact of the Geant4-DNA physics models and JC detector performance on the ionization cluster size distributions (ICSD). ICSD parameters characterize the quality of radiation field and are supposed to be correlated to the complexity of the initial DNA damage in nanoscale and eventually the response of biological systems to radiation. We compared Monte Carlo simulations of ICSD in JC geometry performed using Geant4-DNA and PTra codes with experimental data collected for alpha particles at 3.8 MeV. We investigated the impact of simulation and experimental settings, i.e., three Geant4-DNA physics models, three sizes of a nanometer sensitive volume, gas to water density scaling procedure, JC ion extraction efficiency and the presence of passive components of the detector on the ICSD and their parameters. We found that ICSD in JC geometry obtained from Geant4-DNA simulations in water correspond well to ICSD measurements in nitrogen gas for all investigated settings, while the best agreement is for Geant4-DNA physics option 4. This work also discusses the accuracy and robustness of ICSD parameters in the context of the application of track structure simulation methods for treatment planning in particle therapy.

Ionization Detail Parameters for DNA Damage Evaluation in Charged Particle Radiotherapy: Simulation Study Based on Cell Survival Database

“…The accuracy and robustness of the used Monte Carlo models were first estimated by the comparison with nanodosimetric experiments presented in Appendix B. These simulations are based on the Jet Counter Monte Carlo simulation presented earlier for α particles [39] and recently extended to carbon ions [24]. This simulation code was built using the Geant4 (ver.…”

“…The comparison between ICSDs obtained using Geant4-DNA MC code and those measured with Jet Counter nanodosimeter (JC) is presented in Figure A5. Details of the performed simulations and experiments can be found in [24,39]. The discrepancy between experimental data and simulations is more noticeable in the tails of the ionization cluster size distribution corresponding to large ionization clusters.…”

“…The prediction of ICSD and their parameters based on Geant4-DNA simulations is satisfying and accurate enough to describe experimental data collected with Jet Counter for different charged particles (protons, alpha particles, and carbon ions) in a wide range of energies [24,39]. Our results indicate that the prediction of ICSD and their parameters based on Geant4-DNA Monte Carlo simulations is precise and opens the possibility of its application for other kinds and energies of the ionizing particles presented in this study.…”

Ionization detail parameters and cluster dose: a mathematical model for selection of nanodosimetric quantities for use in treatment planning in charged particle radiotherapy

“…However, this does not preclude the presence of systematic uncertainties, such as uncertainties in interaction cross-sections used in MCTS calculations (see, e.g. Pietrzak et al (2021)). Frequency ICSD are known to vary with the choice of radiation source and sensitive volume geometry.…”