Annular energy and radial dose distributions study for a wide range of ions of different equal LET groups in water

Abstract

Annular energy distribution, AED is a new concept deduced from radial dose, RDD that enables one to draw a map of energy-dose distribution around the ion's path at the nanometer scale better than the ordinary radial dose. The distribution of energy for different equal LET groups of ions of the same LET (keV/μm) were studied using this concept. Annular energy distributions, AEDs for 185 ions impeded in water medium were studied using Katz radial dose formula. AED was calculated using Butts-Katz and Tabata electron range-energy (R-E) relations and were compared. AED and shell annular energy distribution, SAED for those ions were mapping and confirming that energy distributions for ions of the same LET are not the same. AED growth with annular width r=0.1(nm)⟶Rmin(nm) showing a peak at the maximum annular energy width, rMAEW. Butts-Katz and Tabata show same annular energy distribution peaks of the same value, however, Tabata shows that energy is distributed over a wide range than Butts-Katz. Thus, Butts-Katz R-E relation is recommended and considered. AED for the studied 185 ions shows a peak at certain width called the maximum annular energy width, rMAEW. This rMAEW showed a monotonic increasing function with ion's β2. The total annular energy distribution, TAED for the different ions were determined and it shows a linear increasing function of the ion's (Z*/β)2.