A new direction to achieve ultra-fast timing for positron emission tomography

项目摘要/摘要 我们提出了一种新的正电子发射断层扫描电离辐射探测机制。 (PET)使用光学性质的调制而不是闪烁，最终目标是实现更少 大于10皮秒(Ps)湮没光子对符合时间分辨率，这是一个数量级 比最先进的基于闪烁的PET探测器更好。 宠物是一种每天在世界各地使用的非侵入性成像技术，使可视化成为可能 以及在临床和生物学中对活体受试者的疾病分子特征进行量化 研究。一项PET研究包括收集数百万个湮没光子对，这些光子对来自 正电子发射放射性核素标记造影剂注入患者体内。双光子撞击被记录下来 并用于重建表示示踪剂生物分布的3D图像体积。 如果成功，建议的10ps符合时间分辨率将代表着一个巨大的范例 转变为PET，因为它将彻底改变PET系统的运行方式。由此产生的引人注目的 飞行时间(ToF)能力将带来比现有系统更大的信号放大。巨大的 可以利用图像信噪比(SNR)提升来大大增强病变检测，例如 对比度与背景比低的病变；显著减少患者注射剂量和患者扫描 持续时间，可能开启新的临床和研究角色，而PET目前根本没有参与其中； 或者为空间分辨率大大提高的全新PET系统设计铺平道路。 在之前进行的研究中，我们已经表明电离辐射可以调制光学性质， 例如，探测器材料的折射率。我们发现，调制信号的幅度是 线性依赖于事件检测率和平均光子能量。在这个项目中，我们将致力于 进一步探索检测单个511keV光子相互作用的光学性质调制机制， 并研究了该探测概念的时序特性，目标是实现&lt；10ps符合 时间分辨率。我们首先提出了利用511keV光子的机制来实现对单个511keV光子的探测。 通过开发新的方法来放大调制信号和检测来实现光学特性调制 敏感度显著提高的系统。然后，我们计划研究光的本征时间特性 特性调制过程及实现&lt；10ps符合时间分辨率的方法探索 511keV光子相互作用。为了达到最终目的，我们将学习如何使用这种电离辐射的新机制 检测，建立一个实用的，“可平铺”的ToF-PET检测元件。这是一个令人兴奋的多学科项目。 这借鉴了现代光学领域的想法，目标是实现ToF-PET的实质性改进 推动疾病研究和临床管理取得重要进展的绩效。

PROJECT SUMMARY/ABSTRACT We propose to explore a new mechanism of ionizing radiation detection for positron emission tomography (PET) using the modulation of optical properties instead of scintillation, with the ultimate goal to achieve less than 10 picosecond (ps) annihilation photon pair coincidence time resolution, which is an order of magnitude better than possible with state-of-the-art scintillation based PET detectors. PET is a non-invasive imaging technology used every day throughout the world that enables visualization and quantification of the molecular signatures of disease in living subjects in the clinic as well as in biological research. A PET study comprises the collection of millions of annihilation photon pairs emitted from a positron-emitting radionuclide-labeled contrast agent injected into the patient. The two-photon hits are recorded by the system detectors and used to reconstruct a 3D image volume that represents the tracer biodistribution. If successful, the proposed < 10 ps coincidence time resolution would represent a tremendous paradigm shift for PET as it would drastically change the way a PET system operates. The resulting remarkable time-of-flight (ToF) capability will bring substantial signal amplification over existing systems. The enormous image signal-to-noise ratio (SNR) boost can be exploited to greatly enhance lesion detection, for example, for lesions with low contrast-to-background ratio; significantly reduce both patient injected dose and patient scan duration, potentially opening new clinical and research roles for which PET currently has no involvement at all; or pave the way for completely new PET system designs with greatly improved spatial resolution. In previous studies performed, we have shown that ionizing radiation can modulate optical properties, for example, the refractive index, of a detector material. We have found that the modulation signal amplitude is linearly dependent on both the event detection rate and average photon energy. In this project, we will work on further exploring mechanisms of optical property modulation to detect individual 511 keV photon interactions, and study the timing properties of this proposed detection concept with the goal to achieve < 10 ps coincidence time resolution. We first propose to achieve the detection of individual 511 keV photons using the mechanism of optical property modulation by developing novel methods to amplify the modulation signal and detection systems with significantly improved sensitivity. Then we plan to study the intrinsic timing properties of the optical property modulation process and explore methods to achieve < 10 ps coincidence time resolution for coincident 511 keV photon interactions. For the final aim, we will learn how to use this new mechanism of ionizing radiation detection to build a practical, “tileable” ToF-PET detection element. This is an exciting multi-disciplinary project that borrows ideas from the field of modern optics with a goal of enabling substantial improvements in ToF-PET performance to drive important advances in the study and clinical management of disease.