Thin film dosimeters based on Rose Bengal dyed poly(vinyl alcohol)

Abstract

Dyed poly(vinyl alcohol) (PVA) films were prepared by casting the aqueous solutions of PVA incorporating Rose Bengal (RB) dye with or without chloral hydrate on a horizontal glass plate. Such films are useful as routine high-dose dosimeters. These flexible plastic film dosimeters are bleached when exposed to n -ray photons. The useful range of application of these films depends on the concentration of chloral hydrate. RB/PVA film without chloral hydrate is suitable for application in the range of absorbed doses 10-150 kGy. The maximum range of RB/PVA films containing chloral hydrate ranges from 5 to 20 kGy depending on, and inversely proportional to, chloral hydrate concentration in the film. The radiation-chemical yield (G-value) of films was calculated to be in the range from 0.272 to 10.3 µmol/J, where it increases with the increase of both RB and chloral hydrate concentration in the film. The effects of temperature and relative humidity during irradiation as well as pre- and post-irradiation storage, on the radiation response of films are studied. Although, the response of these films depends on relative humidity during irradiation, they are highly stable for long times before and after irradiation when stored in dark and they are not affected by temperature that ranged from 0°C to 45°C during irradiation.