Exploring the Benefits of Time-of-Flight PET

描述(申请人提供)：简单的理论预测，添加飞行时间(TOF)信息可以降低PET图像中的噪声。这种降噪可以改善图像质量、减少成像时间、减少注射剂量，或者实现这些好处的组合。这对转化医学的潜在影响是巨大的，特别是对于大患者的肿瘤学研究，迫切需要改进。因此，随着过去五年TOF PET相机的商业化，飞行时间PET受到了相当大的兴趣。所有这些商用TOF PET相机都达到了~555ps fwm的定时分辨率，但由于图像中的噪声变化与定时分辨率成正比(即，将定时分辨率降低两倍意味着成像时间或剂量减少两倍)，因此需要尽可能获得最佳的定时分辨率。此外，这种降噪如何转化为临床益处还不是很清楚。该建议的目的是构建一台计时分辨率为~150 ps FWHM的PET原型相机(几乎是商用TOF PET相机的四倍)，设计方法来量化飞行时间带来的降噪如何转化为临床益处，然后测量(使用原型相机)图像改善如何依赖于计时分辨率。通过设计获得更好的时间分辨率的方法，并将TOF的好处量化为时间分辨率的函数，我们将通过允许未来的商业和学术TOF PET相机设计师做出明智的选择来指导他们，因为我们的技术开发已经并将继续是“开源”的。我们计划了三个主要的发展。在之前的资金周期中，我们用LSO闪烁体晶体建造了一台单环TOF PET相机，达到了326 ps的符合时间分辨率。虽然简单的估计，与商用的TOF PET相机相比，它将把全身成像中的噪声方差降低大约两倍，但首先要做的是进行彻底的分析，以更好地描述其临床用途。具体地说，我们将使用模拟、体模和人体受试者研究的组合来量化噪声改善作为时间分辨率的函数，包括临床相关的肿瘤检测和分期任务。我们的第二项任务是 使用新开发的闪烁体(LaBr3：Ce)重建相机，该闪烁体具有卓越的PET性能(高灵敏度、3%的能量分辨率和150 ps的计时分辨率)，这将提供比我们的LSO相机更高的计时分辨率的另一个因素。这种计时分辨率几乎是商用TOF PET相机的四倍，我们预测与传统(非TOF)PET相机相比，它将提供巨大的噪声差异减少(当为直径35厘米的患者成像时，降低16倍)！最后一项任务是使用与第一项任务相同的方法来分析该摄像头的性能。

DESCRIPTION (provided by applicant): Simple theory predicts that adding time-of-flight (TOF) information reduces the noise in PET images. This noise reduction can improve image quality, decrease imaging time, decrease injected dose, or achieve a combination of these benefits. The potential impact on translational medicine is large, especially for oncology studies in large patients, where improvement is sorely needed. Thus, time-of-flight PET has received considerable interest, with commercialization of TOF PET cameras in the last five years. All of these commercial TOF PET cameras achieve ~555 ps fwhm timing resolution, but as the noise variance in the image is proportional to the timing resolution (i.e., reducing the timing resolutio by a factor of two implies a factor of two reduction in either the imaging time or dose), there is desire to obtain the best timing resolution possible. In addition, the way in which this noise reduction translates into clinical benefit is not well understood. The purpose of this proposal is o build a prototype PET camera whose timing resolution is ~150 ps fwhm (almost four times better than what commercial TOF PET cameras achieve), devise methods to quantify how the noise reduction afforded by time-of-flight translates into clinical benefit, and then measure (usin the prototype camera) how image improvement depends on the timing resolution. By devising methods for obtaining better timing resolution and by quantifying the TOF benefits as a function of timing resolution, we will guide future commercial and academic TOF PET camera designers by allowing them to make informed choices, as our technical developments have been and will continue to be "open source." We plan three main developments. In the previous funding cycle, we constructed a single-ring "demonstration" TOF PET camera with LSO scintillator crystals that achieves 326 ps coincidence timing resolution. While simple estimates predict that it will reduce the noise variance by a factor of roughly two in whole-body imaging compared to commercial TOF PET cameras, the first task is to perform a thorough analysis to better characterize its clinical utility. Specifically, we will quantify the improvement in noise as a function of timing resolution using a combination of simulation, phantom, and human subject studies, including the clinically relevant tasks of tumor detection and staging. Our second task is to rebuild the camera with a newly developed scintillator (LaBr3:Ce) that has exceptional PET performance (high sensitivity, 3% energy resolution, and 150 ps timing resolution), which will provide another factor of two improvement in timing resolution over our LSO camera. This timing resolution is nearly four times better than commercial TOF PET cameras, and we predict it will give an enormous noise variance reduction (16-fold, when imaging a 35 cm diameter patient) compared to conventional (non-TOF) PET cameras! The final task is to analyze the performance of this camera by using the same methods as in the first task.