The consideration of biological effectiveness of low energy protons using biophysical modeling of the effects induced by exposure of V79 cells

Abstract

We have applied Monte Carlo track structure simulations to estimate relative biological effectiveness (RBE) of low-energy protons using biophysical modelling of radiation effects induced by exposure of V79 cells growing in mono-layer. The microscopic energy deposition in cell nucleus and sub-nucleus volumes was investigated in order to understand the reasons of enhanced biological effectiveness near Bragg peak. Theoretical estimations of RBE based on frequency/dose average lineal energy and calculated yields of initial DNA breaks were collated with experimental RBEM data. It was found: (1) dose average lineal energy for whole cell nucleus as a function of proton energy shows a distinct peak at 550 keV; (2) the peak values for subnucleus volumes are large compared with the whole cell nucleus; (3) the yield of complex DNA breaks correlates with experimental RBEM data.