Inactivation cross sections for mammalian cells exposed to charged particles: a phenomenological approach

Published data on inactivation of V79 cells irradiated with monoenergetic proton and ion beams (He, C, O, Ne) have been analysed. Values for RBEa, RBE10% and the inactivation cross section s have been evaluated in the LET range between 5 and 400 keV.μm-1. RBE against LET curves and inactivation cross sections against LET and against Z*2/β2 curves have been studied in a comparative approach with respect to the different ion types. RBE-LET curves depend strongly on the type of ion for LET>30 keV.μm-1. At LET<30 keV.μm-1 and low doses protons show the greatest effectiveness: at LET>30 keV.μ-1 and high doses He ions provide the most effective radiation. Apart from protons, separation among the various ion curves is less marked in the s against Z*2/β2 plot that in the s against LET plot, s against Z*2/β2 curves for ions with 2(Z(10 and 200<Z*2/β2 <1500 show a common trend independent of Z and are well represented by a linear relationship. (author)