Microdosimetry and Dose-Averaged LET Calculations of Protons in Liquid Water: A Novel Geant4-DNA Application

The spatial distribution of energy deposition events is an essential aspect in the determination radiobiological effects ionizing radiation at cellular level. Microdosimetry provides a theoretical framework for description these events, and has been used several studies to address problems such as characterization Linear Energy Transfer (LET) Relative Biological Effectiveness (RBE) ion beams proton therapy applications. quantities their distributions can be obtained by means Monte Carlo simulations. In this work, we present track structure (MC) application, based on Geant4-DNA, computation microdosimetric protons liquid water. This application two sampling methods uniform weighted , scoring interest spherical sites, with diameters ranging from 1 10 μm. As element novelty, work shows approach followed calculate, without resorting dedicated simulations, imparted site per electronic collision proton, which obtain macroscopic dose-averaged LET proposed Kellerer. Furthermore, concept effective mean chord length take into account δ-ray influx escape calculation segments retrieve agreement predicted Kellerer’s formula. Finally, results demonstrate that our MC reliable computational-efficient perform calculations