Radial dose distribution and effective delta ray radius (Penumbra radius): Determination for some ions passing through water

An analytical equation for calculating radial dose of heavy ions in water is introduced by Awad et al. (Applied Radiation and Isotopes, 142 (2018) 135-142. It is simple alternative to Monte Carlo code and is a promising code, however, still needs refinement. Refinement was added through adjusting radial dose integration upper limit which gives the effective delta-ray range, rmax and ions penumbra radius in water as well. Radial dose distributions for 85 ions forming fifteen energy groups from 0.25 to 24 MeV/n were studied. By employing the effective delta-ray range, it was possible to get more consistent radial dose distribution in comparison to experimental and Monte Carlo simulation data. The corresponding LET values of those ions were estimated and compared with SRIM program. Penumbra radii for 85 ions were determined. Good description for the penumbra radii was obtained using a proposed new equation which fits experimental data as well.