Destructive backscatter-based readout of polymer gel dosimeters: Proof of principle

Abstract

A new method is introduced for evaluating the radiation-induced polymer distributions in polymer gel dosimeters. Destructive backscatter-based readout (DBBR) involves the careful slicing and scanning of dosimeters using dual chromatic scans (e.g., red and blue). Spectral differences in scatter attenuation coefficients cause blue light to be more likely to be scattered by polymers than red light. Comparing the intensities of backscattered red and blue photons allows one to evaluate polymer density. Two polymer gel dosimeters were irradiated, sliced and scanned using the DBBR method. Scans of central slices in two different irradiation patterns were acquired using a flatbed scanner, and [‘blue channel’ – ‘red channel’] images were used to measure polymer distributions. DBBR scan results were then compared against dose distributions calculated by treatment planning software, and select regions of interest from each scan allowed for a quantitative comparison between DBBR values and dose. For comparison, reconstructions were also obtained for the same dosimeters (prior to their destruction) using a fan-beam optical computed tomography scanner.