A RADIOCHROMIC FILM DOSIMETER FOR GAMMA-RADIATION IN THE ABSORBED-DOSE RANGE 0.1-10-KGY

A commercially available leuco-dye film (FWT-63-02), having a thickness of 0.55 mm, has been investigated spectrophotometrically for its characteristics as a radiochromic dosimeter and for its potential use in food-irradiation applications. The gamma-ray irradiation of the nearly colorless, transparent film induces blue color with an absorption maximum at 600 nm. The increase in absorbance at 600 nm per unit thickness of film (DELTA-A mm-1) is linear with dose in the dose range up to 8 kGy, with a slope of 0.91 mm-1.kGy-1. After a modest additional increase during the first day following irradiation, the radiation-induced color is stable when stored at room temperature at least for 5 weeks. The response slope is 16% higher when stored at 60-degrees-C, however, after the initial 1-day increase it is stable for several weeks when stored at that temperature. The response of the dosimeter is independent of dose rate in the range 0.5-170 Gy min-1.