Instituto de Instrumentación para Imagen Molecular, Universitat Politècnica de València-CIEMAT, Valencia, Spain.
Med Phys. 2012 Feb;39(2):643-53. doi: 10.1118/1.3673771.
The authors have developed a small animal Positron emission tomography (PET) scanner based on monolithic LYSO crystals coupled to multi-anode photomultiplier tubes (MA-PMTs). In this study, the authors report on the design, calibration procedure, and performance evaluation of a PET system that the authors have developed using this innovative nonpixelated detector design.
The scanner is made up of eight compact modules forming an octagon with an axial field of view (FOV) of 40 mm and a transaxial FOV of 80 mm diameter. In order to fully determine its performance, a recently issued National Electrical Manufacturers Association (NEMA) NU-4 protocol, specifically developed for small animal PET scanners, has been followed. By measuring the width of light distribution collected in the MA-PMT the authors are able to determine depth of interaction (DOI), thus making the proper identification of lines of response (LORs) with large incidence angles possible. PET performances are compared with those obtained with currently commercially available small animal PET scanners.
At axial center when the point-like source is located at 5 mm from the radial center, the spatial resolution measured was 1.65, 1.80, and 1.86 mm full width at half maximum (FWHM) for radial, tangential, and axial image profiles, respectively. A system scatter fraction of 7.5% (mouse-like phantom) and 13% (rat-like phantom) was obtained, while the maximum noise equivalent count rate (NECR) was 16.9 kcps at 12.7 MBq (0.37 MBq/ml) for mouse-like phantom and 12.8 kcps at 12.4 MBq (0.042 MBq/ml) for rat-like phantom The peak absolute sensitivity in the center of the FOV is 2% for a 30% peak energy window. Several animal images are also presented.
The overall performance of our small animal PET is comparable to that obtained with much more complex crystal pixelated PET systems. Moreover, the new proposed PET produces high-quality images suitable for studies with small animals.
作者开发了一种基于整体 LYSO 晶体与多阳极光电倍增管（MA-PMT）耦合的小动物正电子发射断层扫描（PET）扫描仪。在本研究中，作者报告了一种 PET 系统的设计、校准程序和性能评估，该系统使用这种创新的非像素化探测器设计开发。
该扫描仪由八个紧凑的模块组成，形成一个八边形，轴向视野（FOV）为 40mm，横向 FOV 为 80mm 直径。为了充分确定其性能，遵循了最近发布的专门为小动物 PET 扫描仪制定的美国电器制造商协会（NEMA）NU-4 协议。通过测量在 MA-PMT 中收集的光分布的宽度，作者能够确定相互作用深度（DOI），从而可以正确识别具有大入射角的线响应（LOR）。将 PET 性能与目前市售的小动物 PET 扫描仪的性能进行比较。
在轴向中心，当点状源位于径向中心 5mm 处时，在径向、切向和轴向图像轮廓中分别测量到 1.65、1.80 和 1.86mm 的半最大值全宽（FWHM）空间分辨率。获得了 7.5%（鼠类模拟体）和 13%（大鼠模拟体）的系统散射分数，而最大噪声等效计数率（NECR）在 12.7MBq（0.37MBq/ml）时为 16.9kcps（鼠类模拟体），在 12.4MBq（0.042MBq/ml）时为 12.8kcps（大鼠模拟体）。在 FOV 中心的峰值绝对灵敏度为 30%峰能量窗口的 2%。还呈现了一些动物图像。
我们的小动物 PET 的整体性能可与更复杂的晶体像素化 PET 系统获得的性能相媲美。此外，新提出的 PET 产生了适合小动物研究的高质量图像。
