Exploring a promising design for the next generation time-of-flight PET detector

项目总结/摘要 我们打算研究下一代飞行时间探测器的一个有希望的候选者--正电子发射 断层摄影（PET）湮没光子探测器。通过使重建的 成像信噪比（SNR）和对比度噪声比（CNR），TOF-PET已经证明 对癌症分子特征的可视化和定量的实质性临床影响， 患者特别地，它已被证明在计数不足和缺乏的情况下改善图像质量和准确性。 对比有限的病变检测场景。由TOF提供的有效光子灵敏度提升可以 还可用于显著减少患者的注射剂量和/或研究持续时间， 将使PET在各种临床癌症成像中更实用、更经济、更安全 应用.因此，进一步推进TOF-PET技术的研究，以及光子灵敏度， 总的来说，是非常值得的。改善TOF-PET性能的关键是提高其消光比 光子对符合时间分辨率（CTR）测量之间的任何两个探测元件， 系统，这一直是过去二十年来研究的焦点。目前市售 PET系统实现大约350至800 ps的半高全宽（FWHM）的CTR。这个目标 建议采用新颖的闪烁检测配置以实现100 ps FWHM CTR， 而不损害其它重要的性能参数。这种新颖的配置还使得 常规PET探测器不可能具有的另一种能力：测量能量的能力， 在所述检测器中的一个或多个湮灭光子相互作用的三维（3D）位置。由于 大多数入射的511 keV光子在探测器中经历晶间康普顿散射， 可以利用该过程的运动学来估计光子入射角。如果成功， 能力使我们能够准确地定位这种多晶体事件的第一次相互作用，但也提供了 保留通常被常规PET拒绝的光子事件的高部分的潜力 系统，例如单个（未配对）光子、随机符合、组织散射符合，以及 多个（>2）光子符合。因为这些通常被丢弃的事件比 这款3D位置敏感探测器显示， 有望成为另一种大大提高光子灵敏度的方法。如果成功，这将产生巨大的 光子灵敏度增加，沿着的是图像SNR的显著增强，可能达到100 ps CTR将使PET对癌症成像更敏感、更准确和更实用。在这个项目中 我们将设计和开发这些下一代探测器，将这些模块集成到原型中， 部分环形PET系统，并比较该部分环形系统的图像质量和准确性 我们的成像诊所目前安装的最先进的全身TOF-PET系统。

Project Summary/Abstract We propose to study a promising candidate for the next generation time-of-flight (TOF)-positron emission tomography (PET) annihilation photon detector. By enabling significant increases in the reconstructed image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), TOF-PET has demonstrated substantial clinical impact on the visualization and quantification of molecular signatures of cancer in patients. In particular it has been shown to improve image quality and accuracy in count starved and contrast limited lesion detection scenarios. The effective photon sensitivity boost provided by TOF can also be exploited to significantly reduce injected dose to the patient and/or study duration, factors that would make PET more practical, cost-effective, and safe for a variety of clinical cancer imaging applications. Thus, studies that further advance the TOF-PET technique, and photon sensitivity in general, are highly worthwhile. The key to better TOF-PET performance is to improve the annihilation photon pair coincidence time resolution (CTR) measured between any two detection elements in the system, which has been a focus of research for the past two decades. Current commercially available PET systems achieve a CTR of roughly 350 to 800 ps full-width-at-half-maximum (FWHM). A goal of this proposal is to employ a novel scintillation detection configuration in order to achieve 100 ps FWHM CTR, without compromising other important performance parameters. This novel configuration also enables another capability not possible with the conventional PET detector: The ability to measure the energy and three-dimensional (3D) position of one or more annihilation photon interactions in the detector. Owing to the fact that most incoming 511 keV photons undergo inter-crystal Compton scatter in the detectors, we can exploit the kinematics of that process to estimate the photon angle-of-incidence. If successful, that capability enables us to accurately position the first interaction of such multi-crystal events, but also offers the potential to retain a high fraction of photon events that are normally rejected by a conventional PET system, such as single (unpaired) photons, random coincidences, tissue-scatter coincidences, and multiple (>2) photon coincidences. Since these normally-discarded events are over 10-fold more probable than true coincidence events in a standard PET study, this 3D position sensitive detector shows promise as another method to greatly boost photon sensitivity. If successful, this resulting substantial photon sensitivity increase, along with the substantial image SNR enhancement possible with 100 ps CTR would enable PET to be more sensitive, accurate, and practical for cancer imaging. In this project we will design and develop these next-generation detectors, integrate these modules into a prototype partial-ring PET system, and compare image quality and accuracy available with this partial-ring system to a state-of-the-art whole body TOF-PET system currently installed in our imaging clinic.