Timing Performance Evaluation of PMT-Quadrant-Sharing LYSO Detectors for Time-of-Flight PET
Timing Performance Evaluation of PMT-Quadrant-Sharing LYSO Detectors for Time-of-Flight PET
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DOI：
10.1109/tns.2011.2163081
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发表时间：
2011-09
影响因子：
1.8
通讯作者：
S. An;Hongdi Li;Shitao Liu;R. Ramirez;Yuxuan Zhang;Chao Wang;H. Baghaei;W. Wong
中科院分区：
文献类型：
--
作者：
S. An;Hongdi Li;Shitao Liu;R. Ramirez;Yuxuan Zhang;Chao Wang;H. Baghaei;W. Wong
飞行时间（TOF）数据可以通过估计正电子湮没的位置来提高正电子发射断层扫描（PET）相机的成像质量。在本研究中，我们测量了基于光电倍增象限共享（PQS）设计的正硅酸钇钇（LYSO）块的TOF分辨率，该设计没有外部光导，因此比具有光导的传统块设计具有更高的光收集效率。我们研究了三种数字计时方法来实现更好的计时分辨率：常数分数辨别、前沿辨别和线性拟合。应用根据最小均方拟合估计的时间能量校正来最小化由信号形状变化引起的时间行走。两个 13 × 13 块（每个块均由 4 × 4 × 20 mm3 LYSO 晶体制成，具有滨松快速 R9779 PMT（直径 51 毫米））的平均块到块重合定时分辨率估计为 422 ps（半高全宽）。还测试了另一个 13 × 13 块较小的 1.4 × 1.4 × 10 mm3 LYSO 晶体与 Photonis 的常规 19 毫米直径 XP1912 PMT 的耦合，并实现了 527 ps 的平均块到块定时分辨率。这项研究表明，使用 PQS 探测器模块可以获得适合 TOF PET 系统的良好时间分辨率，以及高空间分辨率和较低的 PMT 成本。
Time-of-flight (TOF) data can improve the imaging quality of positron emission tomography (PET) cameras by estimating the location of the positron annihilation. In this study, we measured the TOF resolution of lutetium yttrium orthosilicate (LYSO) blocks based on the photomultiplier-quadrant-sharing (PQS) design, which has no external light guide and therefore has higher light collection efficiency than the conventional block design with a light guide. We investigated three digital timing methods to achieve better timing resolution: constant fraction discrimination, leading edge discrimination, and linear fitting. A time-energy correction, estimated from a least mean square fit, was applied to minimize time walk caused by the variation of signal shapes. The average block-to-block coincidence timing resolution for two 13 ×13 blocks, each made of 4 × 4 × 20 mm3 LYSO crystals, with fast R9779 PMTs from Hamamatsu (51-mm diameter) was estimated to be 422 ps (full width at half maximum). Another 13 × 13 block of smaller 1.4 × 1.4 × 10 mm3 LYSO crystals coupled to regular 19-mm-diameter XP1912 PMTs from Photonis was also tested and an average block-to-block timing resolution of 527 ps was achieved. This study shows that with PQS detector blocks, good time resolution suitable for TOF PET systems can be obtained, as well as high spatial resolution and lower PMT costs.