High optical stability of reusable radiochromic polyvinyl alcohol-iodine gel dosimeter for radiotherapy

Abstract

In this study, a stable reusable radio-chromic gel dosimeter based on a polyvinyl alcohol-sodium iodide complexes (PVA-NaI) and chemical cross-linking agent glutaraldehyde combined with additives of Glucono-δ-lactone and fructose was prepared and improved by the addition of new additive free radical scavenger dimethyl sulfoxide (DMSO). The radio-chromic gels were exposed to high energy photons (X-rays) to various doses up to 30 Gy, with a constant energy of 6 MV, and a dose rate of 200 cGy min−1 using a medical linear accelerator. UV–Vis spectroscopy technique was used to read out the optical changes of unirradiated and irradiated gel samples in terms of absorbance. The gel samples were transparent, and turn to yellow color after irradiation with a peak absorbance response at 355 nm. The color change is directly related to the absorbed dose. The stability of unirradiated as well as irradiated reusabl gels was remarkably improved by the addition of 500 mM DMSO while maintaining a high dose sensitivity. The developed PVA-NaI radio-chromic gel dosimeter possesses a number of desirable features as a dosimeter, including high sensitivity, excellent dose linearity, dose rate and energy independence, and the PVA-NaI radio-chromic gel dosimeter is reusable, where the color can be decolorized by heating.