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: 9420111
• 负责人: CRAIG S LEVIN
• 金额: $ 41.57万
• 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 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9420111
• 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.

项目总结/摘要 根据BRAIN 2025工作组的报告，有必要大幅改善时空 正电子发射断层扫描（PET）的分辨率，以促进靶向的新示踪剂的翻译 神经感受器功能和动态PET成像在毫秒时间尺度上。为了应对这一挑战，我们 我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脑专用PET系统的基本构建块 在这个可行性阶段之后。这种下一代系统设计有望改变 PET在人类神经成像中的应用，重建图像信噪比大幅提高（>10倍） (SNR)和对比噪声比（CNR）。除了采用较小的系统直径（例如32 cm直径）外 与标准的全身PET系统相比，所提出的这种增强是通过两个独特的特征实现的 提出了（1）100皮秒（ps）符合时间分辨率（CTR），以及（2）测量能量的能力， 在所述检测器中的一个或多个湮灭光子相互作用的三维（3D）位置。这两个新 通过高度创新的闪烁探测器配置实现了这些能力， 提议通过精确地测量湮灭光子从其在患者体内的发射点到 探测器，飞行时间（TOF）PET技术能够显着提高图像SNR和CNR，因为它 允许更多的事件沿着系统的检测器响应线被放置得更靠近它们的真实发射点 在图像重建过程中。改善TOF-PET性能的关键是提高其消光比 在系统中的任意两个探测元件之间测量的光子对CTR。当前市售PET 系统实现大约350到800 ps的半高全宽（FWHM）的CTR。100 ps的目标 FWHM CTR本身代表了PET技术的重大进步。但是，新的探测器配置建议， 还实现了传统PET探测器不可能实现的另一种能力。由于多数 入射的511 keV光子在探测器中经历晶间康普顿散射，我们可以利用 来估算光子的入射角。如果成功，这种能力使我们能够准确地 定位这种多晶体事件的第一次相互作用，但也提供了保留高比例的 通常被常规PET系统拒绝的光子事件，诸如单个（未配对）光子、随机 符合、组织散射符合和多（>2）光子符合。因为这些通常被丢弃的 在标准PET研究中，事件的可能性是真正符合事件的10倍以上，该3D位置 灵敏探测器技术显示出作为另一种方法的前景，以大大提高光子灵敏度，从而 重建图像信噪比。在这个项目中，我们将设计和开发两个下一代PET探测器， 将它们集成到MRI兼容检测器模块中。这些模块的性能将被表征 在3特斯拉临床MRI系统的外部和内部，以证明该概念的可行性。