Geant4 is a Monte Carlo toolkit for simulating the interaction of particles with matter, widely used in many fields of physics. The Geant4-DNA extension tracks radiation interactions in liquid water down to the eV scale and models the subsequent production and diffusion of reactive species up to approximately 1 microsecond, making it particularly suited for studying radiation effects on DNA.
However, the redox imbalance caused by the excess of reactive oxygen species (ROS) produced during radiolysis or the enzymatic response that restores cellular homeostasis are not currently accounted for. An enzymatic kinetics extension is presented that adds a fourth simulation stage, chaining directly after the chemistry stage, to model the ROS scavenging pathways and the time evolution of all molecular species involved in the enzymatic reactions. The module provides seven solver modes including stochastic and hybrid approaches, a library of 12 biological pathway networks, and environmental modulation of reaction rates via pH and temperature.
In this talk I will first review the physics of radiation interaction and water radiolysis, then introduce the oxidative stress response and how enzymatic regulation is modelled within the new module. I will present the validation of the solvers against analytical benchmarks, followed by applications to cell-scale irradiation simulations. Finally, a possible application to the investigation of the FLASH effect, whose dose-rate dependence is not explained by standard radiobiology, will be discussed.
StudentSeminar