Leveraging ultra-fast Cherenkov emission in scintillator-based TOF-PET by exploiting photon wavelength classification

通过利用光子波长分类，在基于闪烁体的 TOF-PET 中利用超快切伦科夫发射

• 批准号: 10659114
• 负责人: Javier Caravaca Rodriguez
• 金额: $ 20.19万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10659114
• 关键词: Aluminum; Bismuth; Cardiovascular Diseases; Chlorides; Classification; Coupled; Detection; Diagnosis; Disease; Disparity; Dose; Electrons; Ensure; Event; Future; Gadolinium; Gallium; Gamma Rays; Germanium; Goals; Grant; Hybrids; Image; Image Enhancement; Lead; Light; Malignant Neoplasms; Measures; Modality; Modernization; Motivation; Nature; Noise; Optics; Oxides; Patients; Performance; Photons; Positron; Positron-Emission Tomography; Radioactive; Resolution; Safety; Signal Transduction; System; Techniques; Technology; Thallium; Time; Work; absorption; accurate diagnosis; cancer type; cost effective; design; detector; frontier; high reward; high risk; imaging capabilities; imaging modality; improved; light emission; millimeter; nanosecond; nervous system disorder; new technology; next generation; novel; nuclear imaging; optical spectra; photon-counting detector; prototype; quantum; standard of care; success; transmission process

Project Summary (Abstract) We propose to separate scintillation and Cherenkov photons produced in scintillator crystals to improve the time and energy resolution of time-of-flight positron emission tomography (TOF-PET) detectors far beyond those achieved in state-of-the-art systems. With its pico-molar sensitivity and a few millimeters of spatial resolution, TOF-PET is the leading nuclear imaging modality for a number of diseases, from cancer to neurological and cardiovascular disorders. A significant improvement of the coincidence time resolution (CTR) and energy resolution would boost the signal-to-noise ratio and hence enhance image quality, resulting in more accurate diagnoses, lower patient doses and exposure times, and granting access to a new broad range of applications for TOF-PET. The ultra-fast picosecond emission of Cherenkov light has demonstrated to achieve the best CTR ever reached of 30ps FWHM using PbF2, a pure Cherenkov emitter. However, this provides a very poor energy resolution due to the low light yield of Cherenkov emission. The combination of Cherenkov and scintillation emission has been proposed as a way to obtain both good time and energy resolution, which has been demonstrated in bismuth germanium oxide (BGO), a high stopping power scintillator for PET, to obtain a CTR of 120ps FWHM with an energy resolution of 14%. The main reason why it is very challenging for BGO to reach CTRs of 30ps FHWM is due to the presence of the slower scintillation light and the inability of current detectors to disentangle between Cherenkov and scintillation. Additionally, the difference between the Cherenkov and scintillation light emission spectra, makes it very hard to obtain a BGO detector that provides both good time and energy resolution. We propose to separate Cherenkov and scintillation photons in order to provide a detector that can be optimized independently for each of the signals, maximizing time resolution with Cherenkov and energy resolution with scintillation without hindering each other. This separation can be achieved by exploiting the different emission spectra of each mechanism using dichroic filters, which are able to classify photons by wavelength with a negligible photon loss. This project aims to 1) obtain a CTR of 50ps FWHM and reduce the scintillation background by a factor of 5 through wavelength classification in BGO, 2) increase photon detection efficiency in BGO by at least a factor of 2 without compromising time resolution, and 3) reach a CTR of 30ps FWHM with a 7% energy resolution by leveraging the hybrid Cherenkov-scintillation concept with thallium chloride (TlCl). This project will pioneer the exploration of wavelength information as a way to dramatically improve TOF-PET performance. We will combine this technique with other cutting-edge technologies such as fast or high quantum efficiency photosensors, in order to demonstrate a novel a cost- effective approach to a next generation TOF-PET. Our goal is to enable a new technology that can bring CTR closer to the 10ps FWHM milestone with a good energy resolution in order to be further exploited in future projects for the construction of a full TOF-PET system.

项目概要（摘要） 我们建议将闪烁体晶体中产生的闪烁光子和切伦科夫光子分开，以提高时间 飞行时间正电子发射断层扫描（TOF-PET）探测器的能量分辨率和能量分辨率远远超出这些 在最先进的系统中实现。凭借其皮摩尔级的灵敏度和几毫米的空间分辨率， TOF-PET 是多种疾病的领先核成像方式，从癌症到神经系统疾病和 心血管疾病。重合时间分辨率 (CTR) 和能量显着提高 分辨率将提高信噪比，从而提高图像质量，从而获得更准确的结果 诊断、降低患者剂量和暴露时间，并允许访问新的广泛应用 用于 TOF-PET。切伦科夫光的超快皮秒发射已被证明可以实现最佳的 CTR 使用纯切伦科夫发射器 PbF2 曾达到 30ps FWHM。然而，这提供了非常差的能量 由于切伦科夫发射的光产率较低，因此分辨率较低。切伦科夫和闪烁的结合 发射被提议作为获得良好时间和能量分辨率的一种方式，这已被提出 在氧化铋锗 (BGO)（一种用于 PET 的高阻止本领闪烁体）中进行了演示，获得了 CTR 120ps FWHM，能量分辨率为 14%。 BGO很难达到的主要原因 30ps FHWM 的 CTR 是由于较慢的闪烁光的存在和电流检测器的无能力造成的 解开切伦科夫和闪烁之间的纠缠。此外，切伦科夫和 闪烁光发射光谱，使得很难获得既提供良好时间又提供良好时间和性能的 BGO 探测器。 能量分辨率。我们建议将切伦科夫光子和闪烁光子分开以提供探测器 可以针对每个信号独立优化，利用切伦科夫和最大化时间分辨率 能量分辨率与闪烁互不阻碍。这种分离可以通过利用来实现 使用二向色滤光片的每种机制的不同发射光谱，能够通过以下方式对光子进行分类 波长可忽略不计的光子损失。该项目的目标是 1) 获得 50ps FWHM 的 CTR 并降低 通过 BGO 中的波长分类将闪烁背景提高 5 倍，2) 增加光子 在不影响时间分辨率的情况下，BGO 中的检测效率至少提高 2 倍，并且 3) 达到 通过利用混合切伦科夫闪烁，CTR 为 30ps FWHM，能量分辨率为 7% 氯化铊 (TlCl) 的概念。该项目将引领波长信息的探索 显着提高 TOF-PET 性能的方法。我们将把这项技术与其他尖端技术相结合 技术，如快速或高量子效率光电传感器，以展示一种新颖的成本 下一代 TOF-PET 的有效方法。我们的目标是实现一种可以带来点击率的新技术 更接近 10ps FWHM 里程碑，具有良好的能量分辨率，以便在未来得到进一步利用 建设完整的 TOF-PET 系统的项目。