Improved PET Timing Resolution: Feasibility and Value

改进的 PET 时序分辨率：可行性和价值

• 批准号: 6914934
• 负责人: WILLIAM W MOSES
• 金额: $ 59.64万
• 依托单位: UNIVERSITY OF CALIF-LAWRENC BERKELEY LAB
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6914934
• 关键词: bioengineering /biomedical engineering; bioimaging /biomedical imaging; biomedical equipment development; computer program /software; deoxyglucose; photomultiplier; positron emission tomography; scintillation cameras; time resolved data

DESCRIPTION (provided by applicant): This project will demonstrate that study time or injected dose can be reduced by a factor of up to 5 by using time-of-flight (TOF) information with LSO-based PET cameras. This reduction would be achievable in clinical, whole body images obtained with PET cameras that differ little from existing commercial cameras. Therefore, the potential impact of this development is large, especially for oncology. Time-of-flight PET was extensively studied in the 1980's and the improvement in noise performance well documented. TOF research died in the 1990's, as compromises caused by the scintillator materials capable of performing TOF measurements outweighed the TOF advantages. Since then, a new scintillator material (LSO) has been discovered and is now being incorporated into many commercial PET scanners. LSO does not have the disadvantages of previous TOF scintillators, and has achieved 300 ps fwhm timing resolution in laboratory situations. This timing accuracy would easily enable TOF PET. Other factors, such as improvements in photomultiplier tubes and advances in custom integrated circuits, make TOF PET much more practical to achieve today. Therefore, it is very likely that 500 ps timing resolution could be achieved in commercial LSO-based PET cameras, which would reduce the noise variance by a factor of 5 in whole body imaging. Clinically, this variance reduction could reduce image noise, decrease the injected dose, shorten the imaging time, or provide a combination of these three benefits. The tasks in this proposal will demonstrate that the timing resolution in commercial PET scanners can be improved enough to enable TOF. We will first quantify the timing resolution of the components/factors that limit the coincidence timing resolution in commercial LSO-based PET cameras, such as transit time jitter in the photomultiplier tubes, reflections within the scintillator crystals, and performance of the time measurement electronics (constant fraction discriminators and time-to-digital converter circuits). Next we will design, construct, and characterize replacement components for those items that most degrade the timing resolution. We will use these newly developed components to demonstrate, with an eight detector module prototype, the timing resolution that could be achieved in a commercial system. The final task is to quantify the gains that the measured time-of-flight resolution would bring to a modern PET camera performing a whole-body FDG study. The quantification will be done using both 2-D and 3-D TOF reconstruction algorithms and will quantify the improvement in noise and spatial resolution.

描述（由申请人提供）： 该项目将证明，通过使用基于 LSO 的 PET 相机的飞行时间 (TOF) 信息，研究时间或注射剂量最多可减少 5 倍。这种减少可以在使用 PET 相机获得的临床全身图像中实现，这些图像与现有的商用相机几乎没有什么不同。因此，这一发展的潜在影响很大，特别是对于肿瘤学。飞行时间 PET 在 20 世纪 80 年代得到了广泛的研究，并且噪声性能的改进得到了充分记录。 TOF 研究于 1990 年代消亡，因为能够执行 TOF 测量的闪烁体材料造成的妥协超过了 TOF 的优势。从那时起，一种新的闪烁体材料 (LSO) 被发现，现已被纳入许多商用 PET 扫描仪中。 LSO没有以前的TOF闪烁体的缺点，并且在实验室情况下实现了300 ps fwhm定时分辨率。这种计时精度可以轻松实现 TOF PET。其他因素，例如光电倍增管的改进和定制集成电路的进步，使得 TOF PET 在当今实现起来更加实用。因此，基于 LSO 的商用 PET 相机很可能实现 500 ps 的定时分辨率，这将使全身成像中的噪声方差降低 5 倍。在临床上，这种方差的减少可以减少图像噪声，减少注射剂量，缩短成像时间，或提供这三个好处的组合。该提案中的任务将证明商用 PET 扫描仪的定时分辨率可以提高到足以实现 TOF。我们将首先量化限制商用 LSO PET 相机重合定时分辨率的组件/因素的定时分辨率，例如光电倍增管中的传输时间抖动、闪烁体晶体内的反射以及时间测量电子器件的性能（常数分数鉴别器和时间数字转换器电路）。接下来，我们将为那些最会降低时序分辨率的项目设计、构建和表征替换组件。我们将使用这些新开发的组件，通过八个探测器模块原型来演示在商业系统中可以实现的定时分辨率。最后的任务是量化测量的飞行时间分辨率将为执行全身 FDG 研究的现代 PET 相机带来的增益。量化将使用 2D 和 3D TOF 重建算法完成，并将量化噪声和空间分辨率的改进。