Fast calculation of nanodosimetric quantities in treatment planning of proton and ion therapy.

Fast calculation of nanodosimetric quantities in treatment planning of proton and ion therapy. Phys Med Biol. 2018 Nov 28;63(23):235015 Authors: Ramos-Méndez J, Burigo LN, Schulte R, Chuang C, Faddegon B Abstract Details of the pattern of ionization formed by particle tracks extends knowledge of dose effects on the nanometer scale. Ionization detail (ID), frequently characterized by ionization cluster size distributions (ICSD), is obtained through time-consuming Monte Carlo (MC) track-structure simulations. In this work, TOPAS-nBio was used to generate a highly precise database of biologically significant ID quantities, sampled with randomly oriented 2.3 nm diameter cylinders, 3.4 nm (10 base pairs) long, inside a chromatin-size cylinder, irradiated by 1-1000 MeV/u ions of Z  =  1-8. A macroscopic method developed to utilize the database using condensed-history MC was used to calculate distributions of the ICSD first moment [Formula: see text] and cumulative probability [Formula: see text] in a 20  ×  20  ×  40 cm3 water phantom irradiated with proton and carbon spread-out Bragg peak (SOBP) of 10.5 cm range, 2 cm width. Results were verified against detailed MC track-structure simulations using phase space scored at several depths. ID distributions were then obtained for intensity modulated proton and carbon radiotherapy plans in a digitized anthropomorphic phantom of a base of skull tumor to demo...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research