Radiophotoluminescence Imaging Reader for Passive Dosimetry

Abstract

In this study, we constructed an image reader system for two-dimensional radiation dosimetry based on radiophotoluminescence (RPL). The reader system mainly consists of a Peltier-cooled CMOS camera and an LED excitation source, as well as control units, and it offers an arbitrary excitation wavelength (e.g., 365, 405, 460, 530, and 630 nm) and a wide spectral detection range (200-1000 nm) to be used for a wide range of prototype image detectors having different spectral features. Using the developed system, we were able to successfully obtain X-ray projection images recorded on a commercial RPL detector [Ag-doped phosphate glass (Ag-PG) plate] as well as custom-made prototypes of flexible imaging plates (IPs). Furthermore, the reader system is applicable not only for RPL imaging but also for conventional optically stimulated luminescence (OSL) imaging, which was demonstrated by using a commercial IP for medical diagnosis.

Research Progress of Radio-photoluminescence Materials and Their Applications

“…Kurobori 等 [96] 使用聚焦质子束在 Ag-PG 上写入微 尺度图案，并首次通过双光子共聚焦显微镜与锁模 钛蓝宝石激光器产生的飞秒激光脉冲相结合，对写 入的微尺度图案进行可视化处理和 2D/3D 重建。图 8((a)-( 1~3))显示了使用聚焦质子束在 Ag-PG 上写入 的二维码图案和线、圆、点 2D 图像以及由 35 层点 和线组成的 3D 图像。Harb 等 [97] 也通过飞秒激光写 入技术在含有高浓度氧化银的磷酸盐玻璃中产生银 簇，并利用这些银簇评估 X 射线剂量的范围和灵敏 度，实现灵敏可靠的空间分辨剂量计。Nanto 等 [98] 构建了一个基于 RPL 的 2D 图像读取系统，并将辐 射信息记录在 Ag-PG 上，取得了理想的成像效果， 空间分辨率达到了微米级，且记录的图像信息能够 稳定存储 30 天以上。Nanto 等 [98] 还将 Ag-PG 的 X 射线成像用于生物成像和无损探测， 如图 8(b)所示。 此外，Okada 使用 LiCaAlF6:Sm [71] 和 BaF2-Al2O3-B2O3:Sm [34] 进行了 X 射线成像研究，空间分辨率达 到百微米，如图 8(c, d)所示。…”

“…20 pA [96] ; X-ray imaging of Ag-PG used in (b)-( 1) medical imaging and (b)-( 2) industrial nondestructive testing [98] ; (c) X-ray imaging of LiCaAlF6:Sm with the micron level spatial resolution [71] ; (d) X-ray imaging of BaF2-Al2O3-B2O3:Sm with a spatial resolution of 5 lp/mm (100 μm) [34] ; (e)-(1) X-ray images using a disk-type imaging detector with LiF film [64] ; Two reconstructed dose distribution images using a disk-type Ag-PG detector with (e)-(2) orange and (e)-(3) blue RPL [101] ; (f)-(1) Photographs of a flexible imaging plate made using (Ba1-xSrx)2SiO4:Eu before X-ray irradiation; (f)-(2) The image of the X-ray irradiated imaging plate under UV excitation, the luminous color changes from red to green; X-ray images obtained after (f)-(3) 10 days and (f)-( 4) 28 days at room temperature in the dark [102] Kurobori 等 [99] 在 2012 年基于 Ag-PG 首次提出 一种具有高空间分辨率(1 mm)、高灵敏度(1 mGy)和 无损读出的新型 2D/3D 圆盘式成像探测器，并将记 录的辐射信息通过计算机重建得到 2D/3D 剂量分布 图像。随后，Kurobori 等 [64,100] 利用 Ag-PG 玻璃和 LiF 薄膜，基于其 RPL 特性对得到的辐射信息进行 2D 图像的重建，成功地证明了在大尺寸(Ф80 mm× 1 mm)成像板上具有兼备微米级的高空间分辨率、 覆盖 11 个数量级(Ag-PG：1×10 -6 ~0.1 Gy，LiF： 10~1×10 5 Gy)的宽辐射剂量检测范围以及无损读出 的可能性。图 8((e)-( 1))显示了使用 LiF 薄膜的圆盘 式成像探测器获得的 X 射线成像。此外，Kurobori 等 [101] 还基于 Ag-PG 的蓝色和橙色 RPL 现象，将圆 盘式成像探测器用于 2D/3D X 射线成像，并成功展 示了微米级的高空间分辨率以及跨越三个数量级的 辐射剂量检测范围。图 8((e)-(2, 3))分别显示了使用 橙色和蓝色 RPL 的圆盘式 Ag-PG 探测器获得的两 个重建剂量分布图像。此外，还可以使用共聚焦检 测系统和透明玻璃检测器将不同深度的图像进行组 合，以重建 3D 剂量分布。 相比于 X 射线平板探测器， 柔性 X 射线存储荧 光屏能够在弯曲、狭窄的场所进行 X 射线的成像和 探测。 Yang 等 [102]…”

Optically stimulated luminescence dosimeters: principles, phosphors and applications

“…Recently, Nanto et al 47) have developed an image reader system for two-dimensional radiation dosimetry based on OSL and RPL phenomena. Figure 10 shows the constructed image reader system, where (a) shows the appearance of the system, (b) illustrates the system configuration, (c) shows the LED disk for stimulation and (d) shows the laptop computer, which can be operated by original program coded by LabVIEW, respectively.…”

Analysis of Photoluminescence and Dosimetric Properties of (Ce, Tb)-codoped Magnesium Orthosilicate Single Crystals

“…(5) Currently there are no ideal storage phosphors that have all the above features; therefore, many researchers have continued to develop storage phosphors to improve their properties. (6)(7)(8)(9)(10)(11)(12) Magnesium orthosilicate (Mg 2 SiO 4 ) is a well-known host material of inorganic phosphors because of its stable crystal structure, high physical and chemical stability, and low thermal expansion property. (13) Mg 2 SiO 4 is also a well-known material for storing phosphors for personal dosimetry because Z eff of Mg 2 SiO 4 (11.4) is relatively close to that of human soft tissues.…”