Rapid detection of accidental hand exposure using radiophotoluminescence glass (FD-7) and an overhead scanning system

Workers who use high-intensity radiation sources on a daily basis are at risk of accidently exposing their fingers to high levels of radiation, which can cause acute effects such as skin damage. For the prompt detection of such unexpected severe exposure, we attempted to use the radiochromic reaction of radiophotoluminscence (RPL) glass that can be worn on the fingers with a common overhead scanning system. A plate-shaped RPL glass (FD-7) with the size of 8.0 × 8.0 × 1.5 mm³ used in a commercially available ring-type glass dosimeter was irradiated with X-rays (160 kV, 6.3 mA) at 80–400 Gy, for which RPL measurements were difficult. Radiochromic reactions of FD-7 were visually confirmed on a tracing light board, and the RGB images captured at certain time intervals using an overhead scanner (OHS) were analyzed using image processing software (ImageJ). In addition, time changes in the post-irradiation absorbance spectra were measured using a UV–visible spectrophotometer. The post-irradiation brownish coloration of FD-7 was detected by the naked eye at all doses (≥80 Gy). From the inverted images acquired by the OHS, the color intensity of the blue channel showed the most preferable dose response covering the target dose range. Interestingly, the blue color intensity stabilized immediately after X-ray irradiation without a preheating procedure, which is generally required in RPL glass dosimetry. The spectrophotometry data confirmed the results obtained using the overhead scanning system; the absorbance in the blue color range (430–490 nm) slightly reduced during the period of post-irradiation RPL build-up. These findings highlight the practical advantages of this novel method for monitoring hand exposure.