Dosimetry characterization of nitro-blue tetrazolium polyvinyl butyral films for radiation processing

Nitro-blue tetrazolium polyvinyl butyral film dosimeters (NBT-PVB) were prepared and investigated based on radiation-induced reduction of NBT2+. NBT-PVB film dosimeters containing different concentrations of NBT dye from 1 to 5 mM were prepared in a solution of ethanol. The dosimeters were irradiated with gamma-ray from Co-60 source at doses from 5 up to 55 kGy. UV/vis spectrophotometry was used to investigate the optical density of unirradiated and irradiated films in terms of absorbance at 529 nm. The absorbance increases with absorbed dose up to 55 kGy for NBT-PVB film dosimeters. The dose sensitivity of NBT-PVB film increases strongly with an increase in concentrations of NBT dye. The effects of irradiation temperature, humidity, dose rate and the stability of the response of the films after irradiation were investigated. The influence of irradiation temperature and humidity on the performance of the film was reduced significantly due to the use of PVB as a binder containing NBT dye. (C) 2011 Elsevier Ltd. All rights reserved.