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

项目摘要/摘要 我们建议研究下一代飞行时间(TOF)的一个有前途的候选者--正电子发射 层析成像(PET)湮没光子探测器。通过显著增加重建后的 图像信噪比(SNR)和对比噪声比(CNR)，TOF-PET已经证明 癌症分子特征的可视化和量化在临床上的重大影响 病人。特别是，它已经被证明在计数饥饿和 对比有限的病变检测场景。TOF提供的有效光子灵敏度提升可以 还可以用来显著减少患者的注射剂量和/或研究持续时间，这些因素 将使PET更实用、更具成本效益、更安全地用于各种临床癌症成像 申请。因此，进一步推进TOF-PET技术的研究，以及在 将军，都是非常有价值的。提高TOF-PET性能的关键是提高湮没效率 光子对符合时间分辨率(CTR)测量在任意两个探测元件之间 系统，这在过去二十年里一直是研究的焦点。目前市面上有售 PET系统实现了大约350到800 ps的半高全宽(FWHM)CTR。这是一个目标 建议采用一种新的闪烁检测配置以实现100ps半高宽CTR， 而不会影响其他重要的性能参数。这种新颖的配置还实现了 另一种常规PET探测器无法实现的功能是：测量能量和 探测器中一个或多个湮没光子作用的三维(3D)位置。由于 事实上，大多数进入的511keV光子在探测器中经历晶间康普顿散射，我们 可以利用这一过程的运动学来估计光子入射角。如果成功，那么 功能使我们能够准确定位此类多晶体事件的首次交互，而且还提供 保留通常被常规PET拒绝的高比例光子事件的可能性 系统，例如单(未配对)光子、随机符合、组织散射符合以及 多(&gt；2)个光子重合。因为这些通常被丢弃的事件超过10倍 在标准的PET研究中，这一3D位置敏感探测器显示的可能比真实符合事件 承诺这是另一种极大提高光子灵敏度的方法。如果成功，这将带来大量的 光子敏感度提高，同时100ps的图像信噪比也有可能大幅提高 CTR将使PET在癌症成像中更敏感、更准确、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，将这些模块集成到一个原型中 部分环PET系统，并比较该部分环系统的图像质量和准确度 到目前安装在我们成像诊所的最先进的全身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.