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

项目摘要(摘要) 我们建议分离闪烁体晶体中产生的闪烁光子和切伦科夫光子，以缩短时间。 飞行时间正电子发射断层扫描(TOF-PET)探测器的能量分辨率远远超过 在最先进的系统中实现。凭借其皮摩尔灵敏度和几毫米的空间分辨率， TOF-PET是许多疾病的领先核成像方式，从癌症到神经和 心血管疾病。符合时间分辨率(CTR)和能量的显著提高 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，减少患者剂量和暴露时间，并允许访问新的广泛应用程序 用于TOF-PET。切伦科夫光的超快皮秒发射证明达到了最好的CTR 使用纯切伦科夫发射器PbF2达到了30ps的半高宽。然而，这提供了非常差的能量 由于切伦科夫发射的光产额很低，因此解决了这一问题。切伦科夫与闪烁的结合 排放已经被提出作为获得良好的时间和能量分辨率的一种方式，这已经被 在用于PET的高阻挡能力闪烁体氧化铋(BGO)中展示，以获得CTR 120ps半高宽，能量分辨率为14%。BGO之所以非常具有挑战性的主要原因是 30ps FHWM的CTRS是由于存在较慢的闪烁光和电流探测器不能 解开切伦科夫和闪光之间的纠葛。此外，切伦科夫和切伦科夫之间的区别 闪烁光发射光谱，使得很难获得同时提供良好时间和 能源分辨率。我们建议分离切伦科夫光子和闪烁光子，以便提供一个探测器 可以针对每个信号单独进行优化，使用Cherenkov和 能量分辨率与闪烁互不妨碍。这种分离可以通过利用 每种机制的不同发射光谱使用二向色滤光片，能够通过以下方式对光子进行分类 具有可以忽略的光子损失的波长。该项目的目标是1)获得50ps半高宽的CTR，并降低 BGO中的闪烁背景通过波长分类增加了5倍，2)增加了光子 在不影响时间分辨率的情况下，BGO的检测效率至少提高了2倍，并且3)达到 利用切伦科夫-闪烁体的能量分辨率为7%的30ps半高宽的CTR 与氯化铊(TlCl)的概念。该项目将率先探索波长信息作为一种 显著提高TOF-PET性能的方法。我们将把这项技术与其他尖端技术结合起来 例如快速或高量子效率的光电传感器等技术，以展示一种新型的成本- 下一代TOF-PET的有效方法。我们的目标是实现一种能够带来CTR的新技术 更接近10ps半高宽里程碑，具有良好的能量分辨率，以便在未来进一步开发 建造完整的TOF-PET系统的项目。

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.