Technologies to drastically boost photon sensitivity for brain-dedicated PET

大幅提高大脑专用 PET 光子灵敏度的技术

• 批准号: 9568754
• 负责人: CRAIG S LEVIN
• 金额: $ 41.09万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-25 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9568754
• 关键词: Address; Anatomy; Binding; Brain; Caliber; Clinical; Collection; Compton radiation; Coupled; Crystallization; Data; Detection; Development; Dimensions; Electronics; Elements; Event; Functional Magnetic Resonance Imaging; Goals; Human; Image; Incidence; Income; Length; Light; Magnetic Resonance; Magnetic Resonance Imaging; Measurement; Measures; Methods; Molecular; Neuromodulator; Neurotransmitter Receptor; Neurotransmitters; Noise; Patients; Performance; Photons; Positioning Attribute; Positron-Emission Tomography; Price; Process; Property; Recovery; Reporting; Research; Resolution; Sensory Receptors; Side; Signal Transduction; System; Techniques; Technology; Testing; Time; Tissues; Tracer; Translating; Translations; Width; Work; analog; cost effective; design; detector; digital; image reconstruction; improved; innovation; interest; kinematics; millisecond; neurochemistry; neuroimaging; next generation; novel; operation; photon-counting detector; receptor; receptor function; response; retinal rods; spatiotemporal; targeted treatment; two-dimensional; uptake; working group

Project Summary/Abstract According to the BRAIN 2025 working group report, there is a need to drastically improve the spatiotemporal resolution of positron emission tomography (PET), in order to facilitate the translation of new tracers that target neuroreceptor function and dynamic PET imaging on the milliseconds timescale. To address this challenge, we propose to demonstrate feasibility of a next generation annihilation photon detector module that, if successful, will serve as the fundamental building block of an advanced brain-dedicated PET system to be developed in follow-on work after this feasibility stage. This next-generation system design shows promise to transform the capabilities of PET in human neuroimaging through substantial (>10-fold) boosts in reconstructed image signal-to-noise ratio (SNR) and contrast-to-noise ration (CNR). Besides employing a smaller system diameter (e.g. 32 cm diameter) compared to the standard whole body PET system, this proposed enhancement is enabled by two unique features proposed (1) 100 picosecond (ps) coincidence time resolution (CTR), and (2) the ability to measure the energy and three-dimensional (3D) position of one or more annihilation photon interactions in the detector. These two new capabilities are achieved through a highly innovative scintillation detector configuration described in detail in the proposal. By precisely measuring the flight time of annihilation photons from their emission point within the patient to the detectors, the time-of-flight (TOF) PET technique enables a significant image SNR and CNR boost because it allows more events to be placed closer to their true point of emission along detector response lines of the system during the image reconstruction process. The key to better TOF-PET performance is to improve the annihilation photon pair CTR measured between any two detection elements in the system. Current commercially available PET systems achieve a CTR of roughly 350 to 800 ps full-width-at-half-maximum (FWHM). The proposed goal of 100 ps FWHM CTR alone represents a significant PET technology advance. But the novel detector configuration proposed also enables another capability not possible with the conventional PET 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 possibility 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 technology shows promise as another method to greatly boost photon sensitivity, and thus reconstructed image SNR. In this project we will design and develop two next-generation PET detectors and integrate them into MRI-compatible detector modules. The performance of these modules will be characterized outside and inside a 3 Tesla clinical MRI system to demonstrate feasibility of this concept.

项目概要/摘要 根据BRAIN 2025工作组报告，需要大幅改善时空 正电子发射断层扫描（PET）的分辨率，以促进针对目标的新示踪剂的翻译 神经感受器功能和毫秒时间尺度的动态 PET 成像。为了应对这一挑战，我们 建议证明下一代湮灭光子探测器模块的可行性，如果成功，将 作为后续开发的先进大脑专用 PET 系统的基本构建模块 在此可行性阶段之后进行工作。这种下一代系统设计有望改变以下功能： PET 在人类神经成像中显着提高（>10 倍）重建图像信噪比 （SNR）和对比噪声比（CNR）。除了采用较小的系统直径（例如 32 厘米直径） 与标准全身 PET 系统相比，所提出的增强功能是通过两个独特的功能实现的 提议 (1) 100 皮秒 (ps) 符合时间分辨率 (CTR)，以及 (2) 测量能量和能量的能力 探测器中一个或多个湮灭光子相互作用的三维 (3D) 位置。这两个新 功能是通过高度创新的闪烁探测器配置实现的，详细描述在 提议。通过精确测量湮灭光子从患者体内发射点的飞行时间， 在探测器中，飞行时间 (TOF) PET 技术可显着提高图像 SNR 和 CNR，因为它 允许更多事件沿着系统的探测器响应线放置在更接近其真实发射点的位置 在图像重建过程中。更好的TOF-PET性能的关键是提高湮灭 测量系统中任意两个检测元件之间的光子对 CTR。目前市售的PET 系统的 CTR 约为 350 至 800 ps 半高全宽 (FWHM)。建议的 100 ps 目标 仅 FWHM CTR 就代表了 PET 技术的重大进步。但提出的新颖探测器配置 还实现了传统 PET 探测器无法实现的另一种功能。由于大多数 传入的 511 keV 光子在探测器中经历晶间康普顿散射，我们可以利用以下运动学 该过程估计光子入射角。如果成功的话，这种能力使我们能够准确地 定位此类多晶事件的首次相互作用，但也提供了保留高比例的可能性 通常被传统 PET 系统拒绝的光子事件，例如单（不成对）光子、随机光子 巧合、组织散射巧合和多个（>2）光子巧合。由于这些通常被丢弃的 在标准 PET 研究中，该 3D 位置事件的可能性比真实巧合事件高 10 倍以上 灵敏探测器技术有望成为另一种大大提高光子灵敏度的方法，因此 重建图像信噪比。在这个项目中，我们将设计和开发两种下一代 PET 探测器和 将它们集成到 MRI 兼容的探测器模块中。这些模块的性能将被表征 3 特斯拉临床 MRI 系统的外部和内部，以证明这一概念的可行性。