Reconstruction-free three dimensional positron emission imaging

免重建三维正电子发射成像

• 批准号: 10504837
• 负责人: Sun Il Kwon
• 金额: $ 55.66万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10504837
• 关键词: 3-Dimensional; Algorithms; Anodes; Area; Biomedical Research; Cherenkov Radiation; Clinical; Complement; Computational algorithm; Data; Data Collection; Detection; Development; Diagnostic Neoplasm Staging; Discrimination; Disease; Event; Excision; Eye; Foundations; Fruit; Future; Generations; Glass; Goals; Health; Hospitals; Image; Imaging Device; Lead; Light; Location; Machine Learning; Measures; Monte Carlo Method; Nature; Noise; Optics; Outcome; Patients; Performance; Photons; Physics; Positioning Attribute; Positron; Positron-Emission Tomography; Process; Property; Radiation Dose Unit; Radioisotopes; Reaction Time; Refractive Indices; Resolution; Sampling; Scanning; Series; Signal Transduction; System; Techniques; Three-Dimensional Image; Three-Dimensional Imaging; Time; Translations; Tube; Vision; Weight; Work; base; breast imaging; clinical application; clinical imaging; clinical translation; convolutional neural network; deep learning; design; detection sensitivity; detector; flexibility; heart imaging; human imaging; image reconstruction; imaging platform; imaging system; improved; innovation; instrumentation; machine learning algorithm; novel; personalized care; photomultiplier; portability; preservation; prototype; radiotracer; real-time images; reconstruction; response; scale up; signal processing; simulation; tomography; tool; treatment response

Project Summary/Abstract A major advantage of coincidence detection of annihilation photons from positron-emitting radiotracers is the availability of time-of-flight (TOF) information, and the ability to measure TOF differences to better localize the positron emitter. Normally for positron emission tomography (PET), TOF information is used as a weighting kernel during image reconstruction and results in an effective sensitivity gain that can be used to reduce radiation dose, improve signal-to-noise ratio, or reduce scan duration. The magnitude of these benefits depend on the TOF resolution, which is governed by the timing performance of the detectors. Current state of the art for PET scanners is ~220 ps which corresponds to a localization of ~3.3 cm. A transformational change would occur, however, if a TOF resolution of <30 ps could be achieved. This would localize events within 4.5 mm, allowing images to be directly generated without a reconstruction algorithm at a spatial resolution that matches what is achieved in clinical PET scanners today. We refer to this as direct positron emission imaging (PEI). With this superb TOF resolution and reconstruction-free imaging, we enter a new regime where we expect major increases in image signal-to-noise, both due to the additional TOF information, and the removal of noise amplification inherent in reconstructing noisy data with noisy corrections from projection data. We propose to develop a first proof-of-concept imaging system that uses ultra-fast detectors to directly produces cross-sectional images without reconstruction and to quantify the performance of PEI both through simulations and experimentally. Since direct PEI does not have the same sampling constraints for data collection as PET, it creates opportunities for portable, and flexible imaging devices, with implications for patient-tailored or task-specific imaging applications (i.e. cardiac or breast imaging), as well as open designs for general purpose applications. To achieve the unprecedented TOF capabilities needed for direct PEI, we will exploit promptly emitted Cerenkov radiation that is generated with <10 ps in certain materials, including scintillators, in response to a 511 keV photon interaction. Our proposed novel detector design integrates a Cerenkov radiator directly into the entrance window of an ultra-fast microchannel plate photomultiplier tube, which is the fastest photon detector currently available with a response time of 25 ps. This approach eliminates all optical reflections between the point of light generation and the photocathode, preserving the prompt timing nature of Cerenkov photons. We then combine the integrated Cerenkov radiator detector with auxiliary photodetector read-out for robust coincidence detection, and complement this with advanced signal processing algorithms we have pioneered using convolutional neural networks to extract all possible timing information from the digitized detector waveforms and ultimately to perform reconstruction-free imaging using only the digitized waveforms as input. In summary, we aim to prove that direct PEI is possible, to characterize its properties and to provide the technological and algorithmic foundations for eventual translation for human imaging.

项目概要/摘要 正电子发射放射性示踪剂湮灭光子的符合检测的一个主要优点是 飞行时间 (TOF) 信息的可用性，以及测量 TOF 差异以更好地定位的能力 正电子发射器。通常对于正电子发射断层扫描 (PET)，TOF 信息用作加权 图像重建期间的内核并产生有效的灵敏度增益，可用于减少辐射 剂量、提高信噪比或缩短扫描时间。这些好处的大小取决于 TOF 分辨率，由探测器的定时性能决定。 PET 的最新技术水平 扫描仪的速度约为 220 ps，对应于 ~3.3 cm 的定位。将会发生翻天覆地的变化， 然而，如果可以实现 <30 ps 的 TOF 分辨率。这会将事件定位在 4.5 毫米以内，从而允许 无需重建算法即可直接生成图像，其空间分辨率与实际情况相匹配 如今，临床 PET 扫描仪已实现这一目标。我们将此称为直接正电子发射成像 (PEI)。有了这个 卓越的 TOF 分辨率和免重建成像，我们进入了一个新的领域，我们预计将大幅提高 在图像信噪比中，由于附加的 TOF 信息以及噪声放大的消除 通过投影数据的噪声校正来重建噪声数据是固有的。我们建议开发第一个 使用超快探测器直接生成横截面图像的概念验证成像系统 无需重建，并通过模拟和实验量化 PEI 的性能。 由于直接 PEI 没有与 PET 相同的数据收集采样限制，因此它创造了机会 用于便携式、灵活的成像设备，对患者定制或特定任务成像有影响 应用（即心脏或乳腺成像），以及通用应用的开放式设计。 为了实现直接 PEI 所需的前所未有的 TOF 能力，我们将利用快速发射的 Cerenkov 某些材料（包括闪烁体）响应 511 keV 产生的辐射 <10 ps 光子相互作用。我们提出的新颖探测器设计将切伦科夫散热器直接集成到入口中 超快微通道板光电倍增管的窗口，这是目前最快的光子探测器 响应时间为 25 ps。这种方法消除了光点之间的所有光学反射 生成器和光电阴极，保留了切伦科夫光子的即时计时性质。然后我们结合 集成的切伦科夫辐射探测器具有辅助光电探测器读出功能，可实现强大的重合检测， 并用我们率先使用卷积神经网络的先进信号处理算法来补充这一点 网络从数字化检测器波形中提取所有可能的定时信息，并最终执行 仅使用数字化波形作为输入的免重建成像。总之，我们的目标是证明直接 PEI 可以描述其属性并提供技术和算法基础 最终翻译为人类成像。