First prototyping of a dedicated PET system with the hemisphere detector arrangement
First prototyping of a dedicated PET system with the hemisphere detector arrangement
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DOI：
10.1088/1361-6560/ab012c
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发表时间：
2019-03-01
影响因子：
3.5
通讯作者：
Yamaya, Taiga
中科院分区：
文献类型：
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作者：
Tashima, Hideaki;Yoshida, Eiji;Yamaya, Taiga
对高灵敏度、高分辨率和低成本的脑正电子发射断层扫描（PET）成像的强烈需求有望用于痴呆症的早期诊断，以及一般神经科学研究。因此，我们提出了一种用于高灵敏度脑成像的半球探测器的新几何结构，其中在下巴位置或颈部位置增加一个探测器有助于提高灵敏度均匀性。在这项研究中，我们开发了第一个用于概念验证的原型系统，使用四层相互作用深度探测器，每个探测器由16 x 16 x 4个zr掺杂GSO晶体组成，尺寸为2.8 x 2.8 x 7.5 mm(3)和一个高灵敏度64通道平板光电倍增管。我们用47个探测器组成一个内径为25cm，外径为50cm的半球探测器，每个附加探测器使用7个探测器。54个探测器的总数大约是一个典型的全身PET扫描仪的四分之一。原型系统的半球探测器由多个具有不同数量探测器的环和覆盖顶部的十字形顶部探测器单元实现。性能评价表明，滤波后的反投影法空间分辨率均匀，为3 ~ 4 mm。用迭代法对热棒幻影进行成像测试，能够分辨2.2 mm棒。在接近头部顶部的区域测得峰值灵敏度大于10%，这是在顶部检测器单元的帮助下实现的。此外，我们使用该原型系统，对一名健康志愿者进行了第一次FDG临床测试。结果表明，所提出的几何形状具有实现高灵敏度、高分辨率和低成本脑PET成像的巨大潜力。对于附加探测器的位置，颈部位置的附加探测器可以连续放置在半球探测器上，并对视场施加剂量，因此比下巴位置具有更高的灵敏度和更宽的视场。
A strong demand is expected for high-sensitivity, high-resolution and low-cost brain positron emission tomography (PET) imaging for early diagnosis of dementia, as well as for general neuroscience studies. Therefore, we have proposed novel geometries of a hemisphere detector arrangement for high-sensitivity brain imaging, in which an add-on detector at the chin position or neck position helps in sensitivity uniformity improvement. In this study, we developed the first prototype system for proof-of-concept using four-layer depth-of-interaction detectors, each of which consisted of 16 x 16 x 4 Zr-doped GSO crystals with dimensions of 2.8 x 2.8 x 7.5 mm(3) and a high-sensitivity 64-channel flat-panel photomultiplier tube. We used 47 detectors to form a hemisphere detector with a hemisphere shape of 25 cm inner diameter and 50 cm outer diameter, and we used seven detectors for each of the add-on detectors. The total detector number of 54 was about one-fourth that of a typical whole-body PET scanner. The hemisphere detector for the prototype system was realized by multiple rings having different numbers of detectors and a cross-shaped top detector unit covering the top. Performance evaluation showed uniform spatial resolutions of 3-4 mm by the filtered back-projection method. Imaging tests of a hot-rod phantom done with an iterative method were able to resolve 2.2 mm rods. Peak sensitivity was measured as more than 10% at a region near the top of the head, which was achieved with the help of the top detector unit. In addition, using the prototype system, we performed the first FDG clinical test with a healthy volunteer. The results showed that the proposed geometries had high potential for realizing high-sensitivity, high-resolution, and low-cost brain PET imaging. As for the add-on detector position, it was shown that the neck position resulted in higher sensitivity and wider field of view (FOV) than the chin position because the add-on detector at the neck position can be placed continuously to the hemisphere detector and dose to the FOV.