Quantitative relationship between microdosimetric quantities and plasmid DNA damage induced by auger electrons

Objective. This study investigated the microdosimetric characteristics of auger electrons (AEs) and their DNA damage-related physical properties, specifically evaluating the microdosimetric quantity as a physical predictor of initial DNA damage across different radiation types. Approach. Monte Carlo simulations using OpenTOPAS were conducted to calculate the frequency-mean lineal energy ( y F ) and the dose-mean lineal energy ( y D ) in spherical water targets (radii: 10-500 nm) for monoenergetic electrons (3-15 keV). DNA damage yields were quantified using TOPAS-nBio with a linear plasmid DNA model. The correlations between microdosimetric quantities and DNA damage were analyzed not only for AEs but also for protons and alpha particles to assess the universality of y F and y D as potential biological predictors. Main results. AEs demonstrated a pronounced site-radius dependency for both y F and y D within the 10-100 nm target region. Across these biologically relevant nano-scale targets, both strand break (SB) and double-SB (DSB) yields exhibited strong power-law correlations with microdosimetric quantities ( R 2 ⩾ 0.94 for y F and R 2 ⩾ 0.89 for y D ). Low-energy electrons, protons, and alpha particles aligned along a continuous microdosimetric–damage relationship despite differences in particle identity. Specifically, y F provided a more sensitive physical predictor than y D for Auger electron-induced initial DNA damage in the low-lineal-energy region below 10 keV μ m −1 . Significance. These findings show that y F and y D reflect nanoscale energy-deposition patterns governing initial DNA strand-break induction. This microdosimetry-damage relationship extends to low-energy AEs as well as proton and alpha particles.