Conception of the stochastic structure for heavy charged particle tracks in a medium

A new concept of heavy charged particle track in a tissue-equivalent substance as a statistical set of coordinates of points where inelastic interactions of primary and secondary particles (electrons) with atoms occur is suggested. To reduce the calculation time, the notion af an effective electron source induced by the heavy charged particle is introduced. It is shown that when using the concept suggested the structure of particle track is determined by spectral and angular characteristics of the electron source and bank of electron trajectories. A program for physical simulation of electron slowing- down in the energy range of 20 eV - 30 keV has been created for determination of electron trajectories. Calculational results for spectra of electrons knocked out by 1 MeV protons from different nitrogen atom subshells are considered as an example. Data characterizing electron escape probability when ionizing C and O atoms by 1 MeV protons are given. It is concluded that the approach described permits to calculate statistical distributions of absorbed energy normalized per one primary particle or per a certain radiation dose