Radial distribution of electron spectra from high-energy ions

The average track model describes the response of physical and biological s ystems using radial dose distribution as the key physical descriptor. We re port on an extension of this model to describe the average distribution of electron spectra as a function of radial distance from an ion. We present c alculations of these spectra for ions of identical linear energy transfer ( LET), but dissimilar charge and velocity to evaluate the differences in ele ctron spectra from these ions. To illustrate the usefulness of the radial e lectron spectra for describing effects that are not described by electron d ose, we consider the evaluation of the indirect events in microdosimetric d istributions for ions. We show that folding our average electron spectra mo del with experimentally determined frequency distributions for photons or e lectrons provides a good representation of radial event spectra from high-e nergy ions in 0.5-2 mu m sites.