Time-of-flight positron emission tomography using Cerenkov luminescence in bismuth germanate

总结 正电子发射断层扫描（PET）被广泛用作诊断性分子成像技术，并且清楚地显示了肿瘤的形态学特征。 对人类的医疗保健产生了重大影响。PET技术有了很大的改进 通过采用飞行时间（TOF）能力，该飞行时间能力测量两个511 keV的到达时间的差异， 伽马湮灭射线该TOF信息在空间上约束了事件的起源，从而导致改进的TOF测量。 由于PET扫描中的信噪比（SNR）和有效灵敏度的提高，图像质量得到改善。 然而，闪烁体锗酸铋（BGO）对于PET应用具有比闪烁体锗酸铋（BGO）更好的几个性质。 L（Y）SO的一些特性，如较高的阻止本领和较高的光电分数。BGO也没有后台活动 并且可以以比L（Y）SO更低的成本生产。然而，BGO的一个主要缺点是巧合性差 定时分辨率源于闪烁光子产生的中等光产额和缓慢的衰减时间。 因此，尚未考虑将BGO用于当前一代TOF PET扫描仪。 理论上，当511 keV伽马射线在闪烁体中相互作用时， 由光电或康普顿相互作用释放的高能电子迅速产生。切伦科夫 光子在极短的时间范围内产生，并且比闪烁光子更早，因此， 切伦科夫光子应该为PET提供更好的定时信息。有趣的是，BGO具有导致 它产生的切伦科夫光子比其他光子多。 最近，我们第一次展示了提示切伦科夫光子对时间特性的影响， BGO采用我们的合作伙伴FBK开发的最新一代硅光电倍增管（SiPM）。因此，我们建议 BGO的概念是使用切伦科夫光子来获得即时定时信息，而闪烁光子 为PET提供必要的能量信息。该提案的主要目标是：i）提高一致性 ii）通过检测用于TOF PET应用的更多切伦科夫光子来实现BGO的定时分辨率， 用于由切伦科夫光子和闪烁光子两者产生的信号的减少方法和读出电子设备， 以及iii）最终开发和评估第一个实用的基于BGO的TOF PET探测器模块，其具有5 X 5 cm 2的截面积和≤300 ps FWHM的符合定时分辨率。如果成功的话，这个提议 构成了开发新型BGO TOF PET扫描仪的基础， 目前的PET扫描仪。 * 现有NIH资助（R 01-EB 029633飞行时间正电子发射断层扫描）没有变化 使用锗酸铋中的切伦科夫发光）

SUMMARY Positron emission tomography (PET) is widely used as a diagnostic molecular imaging technique and clearly has had a significant impact on human healthcare. There have been significant improvements in PET technology by employing time-of-flight (TOF) capability that measures the difference in arrival time of the two 511 keV gamma annihilation rays. This TOF information spatially constrains the origin of the event, leading to improved image quality due to the increased signal-to-noise ratio (SNR) and effective sensitivity in the PET scan. The scintillator bismuth germanate (BGO), however, has several better properties for PET applications than L(Y)SO, such as higher stopping power and higher photo-electric fraction. BGO also has no background activity and can be produced at lower cost than L(Y)SO. However, a major drawback of BGO is the poor coincidence timing resolution originating from the moderate light yield and slow decay time of scintillation photon production. Therefore, BGO has not been considered for use in current generation TOF PET scanners. Theoretically, when a 511keV gamma ray interacts in a scintillator, a small number of optical Cerenkov photons are produced promptly by energetic electrons released by photoelectric or Compton interactions. The Cerenkov photons are produced within an extremely short time frame and earlier than scintillation photons, Thus the Cerenkov photons should provide better timing information for PET. Interestingly, BGO has properties that lead to it producing more Cerenkov photons than other scintillators. Recently, we showed, for the first time, the influence of prompt Cerenkov photons on the timing properties of BGO using latest generation silicon photomultipliers (SiPMs) developed by our partner FBK. Thus, our proposed concept for BGO is that Cerenkov photons are used to obtain prompt timing information while scintillation photons provide essential energy information for PET. The major goals of this proposal are i) to improve coincidence timing resolution of BGO by detecting more Cerenkov photons for TOF PET applications, ii) to develop signal reducing methods and read-out electronics for signals generated by both Cerenkov and scintillation photons, and iii) to finally develop and evaluate the first practical BGO-based TOF PET detector modules, which have 5 × 5 cm2 cross-sectional area and a coincidence timing resolution of ≤300 ps FWHM. If successful, this proposal forms the basis for developing novel BGO-based TOF PET scanners with higher sensitivity and lower cost than current PET scanners. *There are no changes from the existing NIH grant (R01-EB029633 Time-of-flight positron emission tomography using Cerenkov luminescence in bismuth germanate)