Scintillation Photon Counting Detectors for 100 ps Time-of-Flight PET Imaging

项目摘要 具有极佳符合时间的临床飞行时间正电子发射断层扫描(TOF-PET)系统 分辨率(CTR)承诺大幅提高有效的511keV光子灵敏度。能够更准确地 沿系统响应线局部化湮灭源约束事件数据，提供改进的信号到 噪声比(SNR)和重建图像质量，使511keV光子更接近其真实状态 起源。这种SNR增强随着CTR的提高而增加，这也是当前PET仪器的一个主要目标 研发的是推系统CTR≤100ps的半高全宽(FWHM)。在这个层面上 性能方面，活动的≤限制为1.5厘米，与 没有TOF功能的系统。支持≤100ps半高宽CTR的先进系统将有效地超过 与最先进的临床TOF-PET相比，有效的511keV系统灵敏度提高了一倍或四倍 系统(250-400 ps半高宽CTR)。因此，推进CTR也是大幅改进系统的一条途径 在不增加检测量和系统成本的情况下提高灵敏度。标准PET探测器，包括分段的 高纵横比闪烁晶体元素阵列无法达到这种水平的性能，并且 最终受限于较差的光收集效率和随深度变化的闪烁光子传输时间抖动 被光电探测器看到的。为了解决这个问题，我们建议开发一种新的探测器读出概念，它允许 要计数的闪烁光子，并为每个光子的第一个到达分配一个唯一的时间戳 光敏像素。我们将在可扩展的PET探测器读数和生产PET方面利用这一新的进步 具有高分辨率、三维定位能力和100ps半高宽CTR的探测器模块 在同样不牺牲511keV光子探测效率的设计中。新的探测器设计将 集成到跨越临床PET系统的整个轴向范围(20厘米)的大面积探测器模块中， 包括前端信号处理和后端数据处理。我们将构建一个断层成像的原型 建立和量化相关的系统性能指标和未来临床系统的成像性能 由这个新的探测器制成。建议的PET探测器技术可以对以下方面产生重大影响 定量PET成像。通过有效灵敏度的显著提高而实现的图像SNR可以 用于显著减少示踪剂剂量和缩短扫描时间/增加患者吞吐量，或更好地 在有重要背景的情况下可视化和量化较小的病变/特征，这是重要的 可使PET更加实用和准确，并有助于扩大其在患者中的作用的功能 管理层。

Project Summary Clinical time-of-flight positron emission tomography (TOF-PET) systems capable of excellent coincidence time resolution (CTR) promise to drastically enhance effective 511 keV photon sensitivity. The ability to more precisely localize annihilation origins along system response lines constrains event data, providing improved signal-to- noise ratio (SNR) and reconstructed image quality by associating 511 keV photons more closely to their true origin. This SNR enhancement increases as CTR is improved, and a major goal of ongoing PET instrumentation research and development is to push system CTR ≤100 ps full-width-at-half-maximum (FWHM). At this level of performance, events are constrained ≤1.5 cm, providing more than a five-fold increase in SNR relative to a system with no TOF capability. Advanced systems capable of ≤100 ps FWHM CTR would effectively more than double or quadruple the effective 511 keV system sensitivity, in comparison to state-of-the-art, clinical TOF-PET systems (250-400 ps FWHM CTR). Thus, advancing CTR is also a pathway for greatly improved system sensitivity without increasing detection volume and system cost. Standard PET detectors comprising segmented arrays of high-aspect-ratio scintillation crystal elements cannot achieve this level of performance and are ultimately limited by poor light collection efficiency and depth-dependent scintillation photon transit time jitter seen by the photodetector. To address this, we propose to develop a new detector readout concept which allows scintillation photons to be counted and a unique timestamp to be assigned for the first arriving photon at each photosensor pixel. We will leverage this new advancement in scalable PET detector readout and produce PET detector modules capable of high resolution, three-dimensional positioning capabilities and 100 ps FWHM CTR in a design that also makes no sacrifices on 511 keV photon detection efficiency. The new detector design will be integrated into large area detector modules that span the full axial extent (>20 cm) of a clinical PET system, including front-end signal and back-end data processing. We will construct a prototype tomographic imaging setup and quantify relevant system performance metrics and the imaging performance of future clinical systems made from this new detector. The proposed PET detector technologies can have a significant impact on quantitative PET imaging. The image SNR enabled by the significant boost in effective sensitivity can be employed to substantially reduce tracer dose and shorten scan time/increase patient throughput, or to better visualize and quantify smaller lesions/features in the presence of significant background, which are important features that can make PET more practical and accurate, as well as help to expand its roles in patient management.