A roadmap for sole Cherenkov radiators with SiPMs in TOF-PET
A roadmap for sole Cherenkov radiators with SiPMs in TOF-PET
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DOI：
10.1088/1361-6560/ac212a
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发表时间：
2021-10-07
影响因子：
3.5
通讯作者：
Auffray, Etiennette
中科院分区：
文献类型：
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作者：
Kratochwil, Nicolaus;Gundacker, Stefan;Auffray, Etiennette
飞行时间正电子发射层析成像可以从切伦科夫辐射给出的非常精确的时间估计中获益，切伦科夫辐射是由重无机闪烁体中511 keV的正电子湮灭伽马相互作用产生的。虽然使用mcp - pmt和黑色切伦科夫散热器已经报道了30 ps全宽半最大（FWHM）的时间分辨率，但这种解决方案有几个缺点，如目前可用的mcp - pmt的高成本和低检测效率。另一方面，硅光电倍增管（SiPMs）不受这些障碍的限制，提供了高的光子探测效率和良好的时间响应。在参考探测器上，利用优化的高频读出和新型时间行走校正装置，评估了不同长度和表面条件下耦合到SiPMs的pb2晶体的定时性能，并特别关注了仅检测到一个切伦科夫光子的固有极限。探测到的切伦科夫光子的平均数量在很大程度上取决于晶体表面状态，从而在低光子时间扩展（即良好的定时性能）和灵敏度之间进行权衡。在511 keV γ -沉积下，计算出2 × 2 × 3mm(3)尺寸的PbF2晶体的本然切伦科夫光子产率为16.5 +/- 3.3。在基于信号摆率的时间行走校正后，假设两个相同的探测器臂重合，并使用所有事件，对于2 x 2 x 20 mm(3) （2 x 2 x 3 mm(3)）尺寸的PbF2晶体，获得了215 ps FWHM （142 ps FWHM）的时间分辨率，而没有校正的时间分辨率为261 ps （190 ps）。仅选择一个被检测到的光子，在3毫米长度下，黑色涂层晶体的单光子重合时间分辨率为113 ps，特氟龙包裹晶体的单光子重合时间分辨率为166 ps，而在20毫米长度下，黑色涂层晶体的单光子重合时间分辨率为145 ps，特氟龙包裹晶体的单光子重合时间分辨率为263 ps。
Time of flight positron emission tomography can strongly benefit from a very accurate time estimator given by Cherenkov radiation, which is produced upon a 511 keV positron-electron annihilation gamma interaction in heavy inorganic scintillators. While time resolution in the order of 30 ps full width at half maximum (FWHM) has been reported using MCP-PMTs and black painted Cherenkov radiators, such solutions have several disadvantages, like high cost and low detection efficiency of nowadays available MCP-PMTs. On the other hand, silicon photomultipliers (SiPMs) are not limited by those obstacles and provide high photon detection efficiency with a decent time response. Timing performance of PbF2 crystals of various lengths and surface conditions coupled to SiPMs was evaluated against a reference detector with an optimized test setup using high-frequency readout and novel time walk correction, with special attention on the intrinsic limits for one detected Cherenkov photon only. The average number of detected Cherenkov photons largely depends on the crystal surface state, resulting in a tradeoff between low photon time spread, thus good timing performance, and sensitivity. An intrinsic Cherenkov photon yield of 16.5 +/- 3.3 was calculated for 2 x 2 x 3 mm(3) sized PbF2 crystals upon 511 keV gamma-deposition. After time walk correction based on the slew rate of the signal, assuming two identical detector arms in coincidence, and using all events, a time resolution of 215 ps FWHM (142 ps FWHM) was obtained for 2 x 2 x 20 mm(3) (2 x 2 x 3 mm(3)) sized PbF2 crystals, compared to 261 ps (190 ps) without correction. Selecting on one detected photon only, a single photon coincidence time resolution of 113 ps FWHM for black painted and 166 ps for Teflon wrapped crystals was measured for 3 mm length, compared to 145 ps (black) and 263 ps (Teflon) for 20 mm length.