Evaluation of a clinical TOF-PET detector design that achieves ≤100 ps coincidence time resolution
Evaluation of a clinical TOF-PET detector design that achieves ≤100 ps coincidence time resolution
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DOI：
10.1088/1361-6560/aac504
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发表时间：
2018-06-01
影响因子：
3.5
通讯作者：
Levin, Craig S.
中科院分区：
文献类型：
--
作者：
Cates, Joshua W.;Levin, Craig S.
商用临床正电子发射断层扫描（PET）探测器采用长（>= 20毫米长）和窄（4-5毫米宽）的闪烁晶体，在其窄端光学耦合到光敏传感器。由于晶体中511 keV光子相互作用深度的变化，这种传统晶棒结构的长宽比和511 keV光子衰减特性在闪烁光收集效率和传递到光电探测器的时间上产生了显著的变化。这些差异对一致性时间分辨率的降低有重要影响。相反，如果将晶体耦合到其长侧的光敏传感器上，则可以实现近乎完全的光收集效率，并且可以减少闪烁光子传输时间抖动。在这项工作中，我们比较了长度为3-20 mm的LGSO:Ce（0.025 mol%）晶体在其短端或长侧面与硅光电倍增管（SiPMs）光学耦合时可实现的符合时间分辨率（CTR）。在这种“侧读出”配置中，使用2.9 x .2.9 x 20 mm(3)晶体耦合到使用前缘时间拾取和单个时序通道的3 x 3 mm(2) SensL-J SiPMs，测量102 +/- 2 ps FWHM的CTR。当相同的晶体在其窄端耦合到单个3x3 mm(2) sipm时，CTR为137 +/- 3 ps FWHM。我们进一步研究了通过Cramer-Rao下限（CRLB）使用侧读的CTR的统计限制，并考虑到正在进行的工作，以进一步改进光敏技术并利用快速现象，最终实现10 ps FWHM CTR。潜在的设计方面的可扩展的前端信号处理读出电子使用这种侧读出配置进行了讨论。总之，我们证明了侧读出配置为100 ps CTR临床PET检测器提供了一个即时解决方案，并减轻了阻碍未来实现10 ps FWHM CTR的因素。
Commercially available clinical positron emission tomography (PET) detectors employ scintillation crystals that are long (>= 20 mm length) and narrow (4-5 mm width) optically coupled on their narrow end to a photosensor. The aspect ratio of this traditional crystal rod configuration and 511 keV photon attenuation properties yield significant variances in scintillation light collection efficiency and transit time to the photodetector, due to variations in the 511 keV photon interaction depth in the crystal. These variances contribute significant to coincidence time resolution degradation. If instead, crystals are coupled to a photosensor on their long side, near-complete light collection efficiency can be achieved, and scintillation photon transit time jitter is reduced. In this work, we compare the achievable coincidence time resolution (CTR) of LGSO:Ce(0.025 mol%) crystals 3-20 mm in length when optically coupled to silicon photomultipliers (SiPMs) on either their short end or long side face. In this 'side readout' configuration, a CTR of 102 +/- 2 ps FWHM was measured with 2.9 x .2.9 x 20 mm(3) crystals coupled to rows of 3 x 3 mm(2) SensL-J SiPMs using leading edge time pickoff and a single timing channel. This is in contrast to a CTR of 137 +/- 3 ps FWHM when the same crystals were coupled to single 3x3 mm(2) SiPMs on their narrow ends. We further study the statistical limit on CTR using side readout via the Cramer-Rao lower bound (CRLB), with consideration given to ongoing work to further improve photosensor technologies and exploit fast phenomena to ultimately achieve 10 ps FWHM CTR. Potential design aspects of scalable front-end signal processing readout electronics using this side readout configuration are discussed. Altogether, we demonstrate that the side readout configuration offers an immediate solution for 100 ps CTR clinical PET detectors and mitigates factors prohibiting future efforts to achieve 10 ps FWHM CTR.