TRACK STRUCTURE AND THE CALCULATION OF BIOLOGICAL EFFECTS OF HEAVY CHARGED-PARTICLES

A new approach for the calculation of biological effects of heavy charged particles is discussed. In cont rast to other models, the biological effect is determined locally as a function of the local dose deposited by the charged particle tracks. Based on measurable quantities like the X-ray survival curve, the radial dose profile within a track and a geometrical description of the cell nucleus, the model is able to predict several high LET specific properties of charge particle beams, like the relationship of inactivation cross sections vs. LET and vs. specific energy; the RBE as a function of energy and atomic number of the particles, including the Z-dependent shift of RBE-maxima, from 30 keV/mu m for protons to 300 keV/mu m for carbon ions; the transition from exponential to shouldered survival curves, depending on the size of the biological object and the corresponding particle fluences.