Aldawood Saad, Castelhano Ines, Gernhäuser Roman, Van Der Kolff Hugh, Lang Christian, Liprandi Silvia, Lutter Rudolf, Maier Ludwig, Marinšek Tim, Schaart Dennis R, Parodi Katia, Thirolf Peter G
Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany ; Department of Physics and Astronomy, King Saud University , Riyadh , Saudi Arabia.
Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany ; Faculty of Science, University of Lisbon , Lisbon , Portugal.
Front Oncol. 2015 Dec 7;5:270. doi: 10.3389/fonc.2015.00270. eCollection 2015.
The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5-3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated (137)Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a (60)Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency.
一块尺寸为50毫米×50毫米×30毫米的整块LaBr3:Ce闪烁晶体与一个位置灵敏多阳极光电倍增管（PMT，滨松H9500）相连，该组合代表了正在研究的用于强子治疗中在线离子（质子）束射程验证的康普顿相机的吸收探测器，对其进行了评估，评估内容包括晶体表面采用吸收性或反射性涂层的情况。本研究涵盖了对能量及与位置相关的能量分辨率的评估，结果表明，对于反射性包裹的晶体，在662 keV能量下其能量分辨率提高了2.5至3.5倍。使用准直的（137）Cs源研究了空间依赖性，结果显示，吸收性包裹晶体的边缘和角落处能量分辨率急剧下降。此外，使用（60）Co源测定反射性涂层和吸收性涂层的时间分辨率分别为273 ps（半高宽）和536 ps（半高宽）。相比之下，吸收性包裹探测器的光电倍增管各段上光振幅分布的光扩散函数（LSF）有所改善。两种包裹方式在与能量相关的光电峰探测效率方面几乎没有差异。
