Analytical investigation of biological response of different tissues to proton beam radiation using phenomenological and biophysical models

In particle radiation therapy , the relative biological effectiveness (RBE) is used to evaluate the biological response of human tissues exposed to radiation. The microdosimetric approach may well determine the distribution of RBE-weighted doses of charged particle beams based on dose-mean specific energy with constant innovations and modifications. In this study, the results obtained from the biophysical model (such as the microdosimetric kinetic model (MKM)) with the determined domain size (r d ) have been compared to phenomenological models (such as the Wedenberg, Carabe, and McNamara models) which do not consider variable domain size. The α (linear term of the cell survival curve) and D 10 (dose value at 10% cell survival fraction) quantities variations as a function of particle linear energy transfer (LET) have been analyzed using different RBE models based on animal cell lines, and human cancer cell lines such as human salivary gland (HSG) and glioma , together with the corresponding experimental data. Besides, the impact of variations in prescribed biological dose on the spread-out Bragg peaks (SOBP) calculated by applying the MKM using various cell lines is indicated. The findings show that the D 10 and α parameters estimated applying the Z 1 D ∗ -based MKM adapt better to the published experimental datasets than those applying the LET-based phenomenological models. The MKM calculations based on microdosimetric specific energy at the treatment planning system (TPS) can be well used to predict the physical and biological properties of heavy-ion beams.