Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110, USA.
Med Phys. 2013 Sep;40(9):092104. doi: 10.1118/1.4817522.
The activator ion (Eu(2+) in KCl:Eu(2+)) plays an important role in the photostimulated luminescence (PSL) mechanism of storage phosphor radiation detectors. In order to design an accurate, effective, and robust detector, it is important to understand how the activator ion concentration affects the structure and, consequently, radiation detection properties of KCl:Eu(2+).
Potassium chloride pellets were fabricated with various amounts of europium dopant (0.01-5.0 mol.% Eu(2+)). Clinical radiation doses were given with a 6 MV linear accelerator. Radiation doses larger than 100 Gy were given with a (137)Cs irradiator. Dose response curves, radiation hardness, and temporal signal stability were measured using a laboratory PSL readout system. The crystal structure of the material was studied using x ray diffraction and luminescence spectroscopy.
The most intense PSL signal was from samples with 1.0 mol.% Eu. However, samples with concentrations higher than 0.05 mol.% Eu exhibited significant degradation in PSL intensity for cumulated doses larger than 3000 Gy. Structural and luminescence spectroscopy showed clear evidence of precipitate phases within the KCl lattice, especially for high activator concentrations. Analysis of PL emission spectra showed that interactions between Eu-Vc dipoles and Eu-Vc trimers could explain trends in PSL sensitivity and radiation hardness observations.
The concentration of the activator ion (Eu(2+)) significantly affects radiation detection properties of the storage phosphor KCl:Eu(2+). An activator concentration between 0.01 and 0.05 mol.% Eu in KCl:Eu(2+) storage phosphor detectors is recommended for linear dose response, good PSL sensitivity, predictable temporal stability, and high reusability for megavoltage radiation detection.
激活剂离子（Eu(2+)在 KCl:Eu(2+)中）在存储磷光体辐射探测器的光激励发光（PSL）机制中起着重要作用。为了设计准确、有效和稳健的探测器，了解激活剂离子浓度如何影响结构，从而影响 KCl:Eu(2+)的辐射探测性能是很重要的。
用不同浓度的铕掺杂剂（0.01-5.0 摩尔%Eu(2+)）制备了氯化钾颗粒。用 6MV 线性加速器给予临床辐射剂量。用（137）Cs 辐照器给予大于 100Gy 的辐射剂量。使用实验室 PSL 读出系统测量剂量响应曲线、辐射硬度和时间信号稳定性。用 X 射线衍射和发光光谱研究材料的晶体结构。
最强烈的 PSL 信号来自于 1.0 摩尔%Eu 的样品。然而，对于累积剂量大于 3000Gy 的样品，浓度高于 0.05 摩尔%Eu 的样品的 PSL 强度显著下降。结构和发光光谱学清楚地表明，在 KCl 晶格中存在沉淀相，特别是对于高激活剂浓度。PL 发射光谱分析表明，Eu-Vc 偶极子和 Eu-Vc 三聚体之间的相互作用可以解释 PSL 灵敏度和辐射硬度观察到的趋势。
激活剂离子（Eu(2+)）的浓度显著影响存储磷光体 KCl:Eu(2+)的辐射探测性能。在 KCl:Eu(2+)存储磷光体探测器中，建议将激活剂浓度保持在 0.01 到 0.05 摩尔%Eu 之间，以实现线性剂量响应、良好的 PSL 灵敏度、可预测的时间稳定性和对兆伏级辐射探测的高可重复性。
