Novel small animal PET scanner using 2.0 mm lead-walled straw detectors

描述（由申请人提供）：分子成像技术是非侵入性研究疾病和体内基本生物过程的最强大工具之一，因此对NIH的使命具有重要意义。正电子发射断层扫描（PET）对分子示踪剂浓度的灵敏度比任何其他成像技术都低几个数量级，具有很大的基本灵敏度优势。此外，PET能够产生严格的定量3D摄取分布，独特地没有衰减和散射效应，这使它比光学成像等其他方法具有另一个强大的优势。由于小鼠是迄今为止分子成像中最受欢迎的物种，因此高分辨率非常重要。市场上有许多基于闪烁体的专用小动物PET扫描仪，但仅限于有用的体积成像分辨率不优于5¿l，并且非常昂贵（50万美元至85万美元）。最近将晶体尺寸减小到提高分辨率性能所需的水平的尝试表明，尽管成本大幅增加，但相互作用深度（DOI）误差会将改进降低到边际水平，这表明该方法是徒劳的。提出了一种基于新型铅壁吸管（LWS）探测器元件的低成本、高分辨率PET扫描仪。与闪烁晶体探测器相比，该技术的生产成本要低很多倍，而且由于每个检测到的伽马射线的位置都精确地定位在3D空间中，因此从根本上说，优越的相机配置可以发挥很大的优势。探测器可以放置在非常靠近被成像物体和事件的位置，在一个大得多的立体角上，提供无与伦比的灵敏度，同时保持对DOI引起的分辨率下降的免疫力。与存在DOI问题的晶体器件不同，LWS器件的分辨率性能与探测器尺寸精确成正比。基于在4毫米吸管引导装置中实现的性能缩放，通过全面的蒙特卡罗研究支持，优化设计的2毫米LWS相机可以达到至少1.2¿l的体积分辨率，并且最近演示的分辨率改进应该可以进一步降低到0.58¿l。此外，使用非常小的28个检测器模块计数，可以实现灵敏度和吞吐量增加4倍。与晶体器件形成鲜明对比的是，LWS相机的设计在整个非常大的视野范围内产生高度均匀的灵敏度和分辨率。可行性将通过建造两个30 - 50厘米长的200根稻草LWS模块来证明。使用旋转龙门架的成像性能将通过幻影测试进行评估。较低的成本结合量子质量的提高将提供一种特殊的新型分子成像工具。

DESCRIPTION (provided by applicant): Molecular imaging techniques are among the most powerful tools for non-invasive investigation of disease and fundamental biological processes in vivo and are therefore of high significance to the mission of the NIH. Positron Emission Tomography (PET) provides sensitivity to molecular tracer concentrations several orders of magnitude less than any other imaging technique offering a large fundamental sensitivity advantage. Also PET is able to produce rigorous quantitative 3D uptake distribution uniquely free of attenuation and scatter effects giving it another strong advantage over other methods such as optical imaging. Since mouse is by far the most popular species in molecular imaging, high resolution is of exceptional importance. A number of commercial scintillator based dedicated small animal PET scanners are on the market but are limited to a useful volumetric imaging resolution of no better than 5 ¿l and are very costly ($500,000 - $850,000). Recent attempts to reduce crystal size to levels needed to improve resolution performance have shown that depth of interaction (DOI) error reduces improvement to marginal levels despite substantial cost increase demonstrating the futility of the approach. Development of a low cost, high resolution PET scanner is proposed based on revolutionary detector elements composed of lead walled straws (LWS). Compared to scintillation crystal detectors, this technology is intrinsically many fold less expensive to produce and because the position of each detected gamma ray is located precisely in 3D space, fundamentally superior camera configurations can be employed to great advantage. Detectors can be placed very close to the imaged subject and events accepted over a substantially larger solid angle providing unparalleled sensitivity while maintaining immunity from resolution degradation caused by DOI. Unlike crystal devices with DOI problems, resolution performance of LWS devices scales precisely with detector dimension. Based on scaling of performance achieved in a 4 mm straw pilot device backed up by a comprehensive Monte Carlo study an optimally designed 2 mm LWS camera can reach at least a volumetric resolution of 1.2 ¿l and with recently demonstrated resolution refinements should achieve a further reduction to 0.58 ¿l. Furthermore using a very small detector module count of 28, a 4 fold increase in sensitivity and throughput can be achieved. In stark contrast to crystal devices the LWS camera design produces highly uniform sensitivity and resolution over its entire very large field of view. Feasibility will be demonstrated by construction of two densely packed 200 straw LWS modules of 30 - 50 cm length. Imaging performance using a rotating gantry will be evaluated through phantom testing. Lower cost combined with quantum improvement in quality will afford an exceptional new molecular imaging tool.