Radiation-induced color bleaching of methyl red in polyvinyl butyral film dosimeter

Radio-chromic film based on polyvinyl butyral (PVB) containing different concentrations of methyl red (MR) dye for 0.125, 0.25 and 0.5 mM has been introduced as high dose dosimeter. The dosimeters were irradiated with gamma ray from 60Co source at doses from 5 to 150 kGy. UV/vis spectrophotometry was used to investigate the optical density of unirradiated and irradiated films in terms of absorbance at 497 nm. The dose sensitivity of MR-PVB film dosimeter increases strongly with increase of absorbed dose as well as increase of concentrations of MR dye. The effects of irradiation temperature, relative humidity, dose rate and the stability of the response of the films after irradiation were investigated and found that these films could be used as routine dosimeter in industrial radiation processing. The useful dose range of developed MR-PVB film dosimeters is in the range of 5-100 kGy. - Highlights: → This manuscript relates to radio-chromic dosimeter for used in high dose radiation processing. → Methyl red MR contains azo group which breaking due to gamma radiation, resulting in color bleaching. → Radio-chromic film PVB containing different concentrations of MR dye has been introduced. → The color bleaching of MR-PVB film dosimeter increases gradually with increasing absorbed dose. → Response of MR-PVB films was slightly affected by irradiation temperature and relative humidity.