Stopping Power and Secondary Electrons in Ion Beam Induced Damage

摘要

The process of ionization induced by energetic ions (~(12)C~(6+) and protons, in particular, in the energy range normally relevant to ion beam cancer therapy), incident on liquid water (main tissue constituent), is discussed. A new parameterization, valid for any ion energy, of the singly-differential ionization cross sections is introduced, based on tuning on experiments the ion penetration depths, after accounting for all the effects related to stopping. The resulting functional allows a fast calculation of the energy spectra of secondary electrons at different depths along the ion's trajectory, including the Bragg peak region. At the same time, this parameterization provides an accurate measure of the stopping power and then penetration depths for a broad range of initial-ion energies within the therapeutically-accepted error.