Monte Carlo simulation of cell inactivation after heavy ion irradiation with the Local Effect Model (LEM) including cluster effects

The Local Effect Model (LEM) represents an integral part of the heavy ion treatment planning software TRiP98 to calculate the biologically equivalent dose. Recently, the incorporation of cluster effects of single strand breaks at large local doses around the center of ion tracks was shown to be of particular importance for the prediction of the relative biological effectiveness (RBE) of the initial slope of cell inactivation experiments [1]. However, in order to apply these modifications to treatment planning, the knowledge about RBE values at doses up to a few Gy is necessary. Additionally, a refinement of the radial dose distribution seems to be appropriate.