Huy N. Tran

Microdosimetry of electrons in liquid water using the low-energy models of Geant4

The biological effects of ionizing radiation at the cellular level are frequently studied using the well-known formalism of microdosimetry, which provides a quantitative description of the stochastic aspects of energy deposition in irradiated media. Energy deposition can be simulated using Monte Carlo codes, some adopting a computationally efficient condensed-history approach, while others follow a more detailed track-structure approach. In this work, we present the simulation of microdosimetry spectra and related quantities (frequency-mean and dose-mean lineal energies) for incident monoenergetic electrons (50u2009eV–10u2009keV) in spheres of liquid water with dimensions comparable to the size of biological targets: base pairs (2u2009nm diameter), nucleosomes (10u2009nm), chromatin fibres (30u2009nm) and chromosomes (300u2009nm). Simulations are performed using the condensed-history low-energy physics models (“Livermore” and “Penelope”) and the track-structure Geant4-DNA physics models, available in the Geant4 Monte Carlo simul...

Geant4‐DNA example applications for track structure simulations in liquid water: A report from the Geant4‐DNA Project

This Special Report presents a description of Geant4-DNA user applications dedicated to the simulation of track structures (TS) in liquid water and associated physical quantities (e.g., range, stopping power, mean free path…). These example applications are included in the Geant4 Monte Carlo toolkit and are available in open access. Each application is described and comparisons to recent international recommendations are shown (e.g., ICRU, MIRD), when available. The influence of physics models available in Geant4-DNA for the simulation of electron interactions in liquid water is discussed. Thanks to these applications, the authors show that the most recent sets of physics models available in Geant4-DNA (the so-called option4 and option 6 sets) enable more accurate simulation of stopping powers, dose point kernels, and W-values in liquid water, than the default set of models (option 2) initially provided in Geant4-DNA. They also serve as reference applications for Geant4-DNA users interested in TS simulations.