Simulation Study of Clinical PET Scanners With Different Geometries, Including TOF and DOI Capabilities

IF 4.6 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING
Gabriel Cañizares;Santiago Jiménez-Serrano;Alejandro Lucero;Constantino Morera-Ballester;Enrique Muñoz;José M. Benlloch;Antonio J. González
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Abstract

Total body positron emission tomography (TB-PET) scanners provide high-quality images due to the large sensitivity. Our motivation is to design a TB-PET system with up to 70 cm axial coverage that mitigates the parallax error degradation by using a detector concept based on semi-monolithic LYSO crystals. Furthermore, this detector approach allows to simultaneously reach an accurate coincidence time resolution (CTR) to enhance the image quality by means of time-of-flight (TOF) reconstruction algorithms. We have simulated and compared two positron emission tomography (PET) prototypes with about 70 cm but a different number of detector rings (7 versus 5). The NEMA NU 2 2018 protocol has been implemented. By correcting the parallax error with the depth-of-interaction (DOI) information, the spatial resolution remains homogeneous and below 3 mm in the entire field of view (FOV), differently from designs based on pixelated crystals. The sensitivity reaches values of 58 and 115 cps/kBq, for the 5 and 7 rings configurations, respectively. The noise equivalent count rate (NECR) was found at 563 kcps/mL. This value is lower than other systems, most likely due to the requirement to process a larger number of channels to characterize the DOI. Percent contrasts obtained for two different phantoms are in general beyond 80% for the largest spheres, nearly 100% for the 7 rings configuration once TOF is applied during the reconstruction process. In conclusion, although the sensitivity and NECR results for the 5-rings configuration are lower compared to the 7-rings approach, its overall performance is enhanced by the addition of TOF and parallax error correction, improving that of conventional Whole Body PET scanners (axial length: 20–30 cm) in terms of image quality.
不同几何结构(包括 TOF 和 DOI 功能)的临床 PET 扫描仪模拟研究
全身正电子发射断层扫描(TB-PET)具有高灵敏度,可提供高质量的图像。我们的动机是设计一种轴向覆盖范围达 70 厘米的 TB-PET 系统,通过使用基于半单片 LYSO 晶体的探测器概念来减轻视差误差的衰减。此外,这种探测器方法还能同时达到精确的重合时间分辨率(CTR),从而通过飞行时间(TOF)重建算法提高图像质量。我们模拟并比较了两个正电子发射断层扫描(PET)原型,它们的距离约为 70 厘米,但探测器环的数量不同(7 对 5)。我们采用了 NEMA NU 2 2018 协议。通过使用相互作用深度(DOI)信息校正视差误差,空间分辨率保持均匀,在整个视场(FOV)中低于 3 毫米,这与基于像素化晶体的设计不同。5 环和 7 环配置的灵敏度分别达到 58 和 115 cps/kBq。噪声等效计数率(NECR)为 563 kcps/mL。该值低于其他系统,很可能是由于需要处理更多通道以确定 DOI 的特征。在重建过程中应用 TOF 后,两种不同模型获得的对比度百分比对于最大的球体一般超过 80%,对于 7 环配置则接近 100%。总之,虽然与 7 环方法相比,5 环配置的灵敏度和 NECR 结果较低,但通过添加 TOF 和视差误差校正,其整体性能得到了提高,在图像质量方面比传统的全身 PET 扫描仪(轴向长度:20-30 厘米)更胜一筹。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
IEEE Transactions on Radiation and Plasma Medical Sciences
IEEE Transactions on Radiation and Plasma Medical Sciences RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING-
CiteScore
8.00
自引率
18.20%
发文量
109
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