Nakamura Masaaki, Chida Koichi, Inaba Yohei, Kobayashi Ryota, Zuguchi Masayuki
Department of Radiological Technology, Faculty of Medicine, School of Health Sciences, Tohoku University, 2-1 Seiryou-machi, Aoba-ku, Sendai 980-8575, Japan.
J Radiol Prot. 2017 Jun 26;37(2):N19-N26. doi: 10.1088/1361-6498/aa6272. Epub 2017 May 10.
There are no feasible real-time and direct skin dosimeters for interventional radiology. One would be available if there were x-ray phosphors that had no brightness change caused by x-ray irradiation, but the emission of the YO:Eu, (Y, Gd, Eu)BO, and YVO:Eu phosphors investigated in our previous study was reduced by x-ray irradiation. We found that the brightness of those phosphors recovered, and the purpose of this study is to investigate their recovery phenomena. It is expected that more kinds of phosphors could be used in x-ray dosimeters if the brightness changes caused by x-rays are elucidated and prevented. Three kinds of phosphors-YO:Eu, (Y, Gd, Eu)BO, and YVO:Eu-were irradiated by x-rays (2 Gy) to reduce their brightness. After the irradiation, brightness changes occurring at room temperature and at 80 °C were investigated. The irradiation reduced the brightness of all the phosphors by 5%-10%, but the brightness of each recovered immediately both at room temperature and at 80 °C. The recovery at 80 °C was faster than that at room temperature, and at both temperatures the recovered brightness remained at 95%-98% of the brightness before the x-ray irradiation. The brightness recovery phenomena of YO:Eu, (Y, Gd, Eu)BO, and YVO:Eu phosphors occurring after brightness deterioration due to x-ray irradiation were found to be more significant at 80 °C than at room temperature. More kinds of phosphors could be used in x-ray scintillation dosimeters if the reasons for the brightness changes caused by x-rays were elucidated.
目前尚无适用于介入放射学的可行的实时直接皮肤剂量计。如果存在受X射线照射后亮度不变的X射线磷光体，就会有这样的剂量计，但我们之前研究中所研究的YO:Eu、(Y,Gd,Eu)BO和YVO:Eu磷光体的发射会因X射线照射而降低。我们发现这些磷光体的亮度会恢复，本研究的目的就是探究它们的恢复现象。如果能阐明并防止X射线引起的亮度变化，预计会有更多种类的磷光体可用于X射线剂量计。三种磷光体——YO:Eu、(Y,Gd,Eu)BO和YVO:Eu——受到X射线（2 Gy）照射以降低其亮度。照射后，研究了在室温及80°C下发生的亮度变化。照射使所有磷光体的亮度降低了5% - 10%，但每种磷光体在室温及80°C下亮度均立即恢复。80°C时的恢复比室温时更快，且在两个温度下恢复后的亮度均保持在X射线照射前亮度的95% - 98%。发现YO:Eu、(Y,Gd,Eu)BO和YVO:Eu磷光体在因X射线照射导致亮度劣化后出现的亮度恢复现象在80°C时比在室温时更显著。如果能阐明X射线引起亮度变化的原因，更多种类的磷光体可用于X射线闪烁剂量计。
