Response of aqueous dichromate and nanoclay dichromate gel dosimeters to carbon ion irradiation

Abstract

We have recently reported the significant reduction of radiation product diffusion by the incorporation of clay nanoparticles into dichromate gel (DCG) dosimeters. In this work, we investigate the influence of the nanoclay addition and gelation on the MRI R1 (1/T1) image response of the dichromate dosimeter to the therapeutic carbon ion beam (12C 6+ 290 MeV/u). The MRI R1 distribution in the aqueous dichromate solution well reproduces physical dose-depth distribution with a high linear-energy-transfer (LET) efficiency. The nanoclay DCG dosimeters, on the other hand, exhibit composition-dependent LET efficiency degradation, while a sharp Bragg peak can still be detected. These results indicate that the nanocomposite gel addition may induce change in the radiation-induced reaction mechanism.