Spectrophotometric analysis of blue polymethylmethacrylate as high-dose dosimeter

Abstract

Locally manufactured polymethylmethacrylate containing a blue dye (blue PMMA) was evaluated spectrophotometrically for use as a high-dose radiation dosimeter. The absorption spectrum of 3 mm thick irradiated blue PMMA shows radiation induced absorption changes in the 300–700 nm range. Calibration curves were drawn at 402, 450, 596 and 612 nm. At 402 and 450 nm, where there is an increase in radiation induced absorption, the response as a function of absorbed dose is linear from 5 to 40 kGy. At the longer wavelengths (596 and 612 nm) there is radiation induced fading of colour and the response is linear in the 5–20 kGy range. The effects of post-irradiation storage time, storage temperature, light and relative humidity during post-irradiation storage on the response were investigated.