Experimental and Calculated Response of a Radiochromic Dye Film Dosimeter to High-LET Radiations

Abstract

Dose-response characteristics were measured for the FWT 60 nylon-base radiochromic dye film dosimeter irradiated with ion beams of 3- and 16-MeV protons, 10-MeV a particles, and 21-MeV 7Li, 42-MeV '4N, and 64-MeV 160 ions. These characteristics were compared with the response to reference low-LET radiations, i.e., 6Co y rays and 10-MeV electrons. The ion beams covered an initial LET range of 28-5430 MeV cm2 g-' corresponding to an average LET in the detector of 28-6740 MeV cm2 g-'. The experimental relative effectiveness (RE) decreased monotonically with zf2f2 from 1.00 for 16-MeV protons to 0.81, 0.55, 0.47, 0.36, and 0.28 for 3MeV protons, a particles, and 7Li, 160, and '4N ions, respectively. The radial dose distribution around the ion path was calculated using two different range-energy relations for the 6 rays: a linear relation r = k, wo and a power-law relation r = k2 . w, where r is the range and o the energy of the 6 rays. Calculations of theoretical RE values, based on the track structure theory of Katz and co-workers, were in good agreement with experimental results. The best agreement (-6.2 to +14.3%) was obtained by using a power-law range-energy relation.