Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America.
Sandia National Laboratories, Livermore, CA, United States of America.
Phys Med Biol. 2024 Feb 13;69(4):045025. doi: 10.1088/1361-6560/ad2125.
Standard signal processing approaches for scintillation detectors in positron emission tomography (PET) derive accurate estimates for 511 keV photon time of interaction and energy imparted to the detection media from aggregate characteristics of electronic pulse shapes. The ultimate realization of a scintillation detector for PET is one that provides a unique timestamp and position for each detected scintillation photon. Detectors with these capabilities enable advanced concepts for three-dimensional (3D) position and time of interaction estimation with methods that exploit the spatiotemporal arrival time kinetics of individual scintillation photons.In this work, we show that taking into consideration the temporal photon emission density of a scintillator, the channel density of an analog silicon photomultiplier (SiPM) array, and employing fast electronic readout with digital signal processing, a detector that counts and timestamps scintillation photons can be realized. To demonstrate this approach, a prototype detector was constructed, comprising multichannel electronic readout for a bismuth germanate (BGO) scintillator coupled to an SiPM array.In proof-of-concept measurements with this detector, we were able to count and provide unique timestamps for 66% of all optical photons, where the remaining 34% (two-or-more-photon pulses) are also independently counted, but each photon bunch shares a common timestamp. We show this detector concept can implement 3D positioning of 511 keV photon interactions and thereby enable corrections for time of interaction estimators. The detector achieved 17.6% energy resolution at 511 keV and 237 ± 10 ps full-width-at-half-maximum coincidence time resolution (CTR) (fast spectral component) versus a reference detector. We outline the methodology, readout, and approach for achieving this detector capability in first-ever, proof-of-concept measurements for scintillation photon counting detector with analog silicon photomultipliers.The presented detector concept is a promising design for large area, high sensitivity TOF-PET detector modules that can implement advanced event positioning and time of interaction estimators, which could push state-of-the-art performance.
用于正电子发射断层扫描（PET）闪烁探测器的标准信号处理方法，从电子脉冲形状的综合特征中，对 511keV 光子相互作用时间和传递给检测介质的能量进行准确估计。最终实现 PET 闪烁探测器，为每个探测到的闪烁光子提供唯一的时间戳和位置。具有这些功能的探测器可以利用单个闪烁光子的时空到达时间动力学，为三维（3D）位置和相互作用时间估计提供先进的概念。在这项工作中，我们表明，考虑到闪烁体的时间光子发射密度、模拟硅光电倍增管（SiPM）阵列的通道密度，并采用快速电子读出和数字信号处理，可以实现对闪烁光子进行计数和时间戳的探测器。为了证明这种方法，构建了一个原型探测器，它包括用于与 SiPM 阵列耦合的锗酸铋（BGO）闪烁体的多通道电子读出。在使用该探测器进行的概念验证测量中，我们能够对所有光光子的 66%进行计数并提供唯一的时间戳，其中剩余的 34%（两个或更多光子脉冲）也被独立计数，但每个光子束共享一个共同的时间戳。我们表明，这种探测器概念可以实现 511keV 光子相互作用的 3D 定位，从而实现对相互作用估计器的校正。该探测器在 511keV 处实现了 17.6%的能量分辨率，237±10ps 全宽半最大值符合时间分辨率（CTR）（快速谱分量）与参考探测器相比。我们概述了在具有模拟硅光电倍增管的闪烁光子计数探测器的首次概念验证测量中实现这种探测器功能的方法、读出和方法。所提出的探测器概念是一种有前途的设计，适用于大面积、高灵敏度的时飞行 PET 探测器模块，可实现先进的事件定位和相互作用时间估计器，从而推动最先进的性能。
