Dose-rate-independent and diffusion-free nanoclay-based radio-fluorogenic gel dosimeter

Abstract

The gel dosimeter is expected to function as a true three-dimensional dosimeter for radiotherapy in tissue equivalent material. To improve sensitivity, a gel dosimeter employing fluorometric dose imaging is proposed. We report a nanoclay-based radiofluorogenic gel (NC-RFG) dosimeter employing dihydrorhodamine 123 (DHR 123), which avoids the main drawbacks of conventional RFG, namely, diffusion of the radiation products, dose rate dependence, and oxygen effects in radiation-induced reactions. The dose responses of the NC-RFG employing DHR 123 under X-ray irradiation were evaluated using a fluorescence spectrometer and 2D fluorescence gel scanner. The results show high linearity within the range 0–5 Gy, and the sensitivity was maintained by increasing the post-irradiation time to 37 days and the dose rate from 3.0 to 10.4 Gy/min. We also discussed the preparation conditions for the clay and radiosensitizers, trichloroacetic acid (TCAA) and Triton X-100. By scanning with a commercially available 2D fluorescence scanner, the 2D dose distribution can be evaluated as it has a linear dose response, and its spatial dose information is maintained for up to 73 days.