Improved performance of radiochromic films for high-dose dosimetry

Radiochromic thin films based on polyvinyl alcohol (PVA) containing different concentrations of methyl red (MR) and methylene blue (MB) dyes were studied for the quantification of high doses. These films were exposed to doses of 100 to 200 kGy. A 137 Cs radiation source was employed for this purpose. The absorption spectra of unirradiated and irradiated dyed PVA films are measured with a UV/VIS spectrophotometer in terms of absorbance at 518 nm for MR-PVA film and 668 nm for MB-PVA film. A strong dependence on the dye concentration of the absorbed dose is observed for high-dose irradiation. It was shown that the MR-PVA film is stable before and after irradiation under dark as well as florescent light as compared with MB-PVA film.