Kuang Zhonghua, Zhang Ling, Ren Ning, Liu Zheng, Deng Haiming, Li Yalan, Niu Ming, Sun Tao, Hu Zhanli, Yang Yongfeng
Microelectronics and Optoelectronics Technology Key Laboratory of Hunan Higher Education, School of Physics and Electronic Electrical Engineering, Xiangnan University, Chenzhou 423000, People's Republic of China.
Chinese Academy of Sciences, Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Shenzhen 518055, People's Republic of China.
Phys Med Biol. 2025 Sep 2;70(17). doi: 10.1088/1361-6560/adfe32.
The probability of 511 keV-rays undergoing inter-crystal scattering (ICS) in current positron emission tomography (PET) detectors is high. The objective of this research is to study the impact of the ICS events on the performance of the small animal SIAT aPET scanner.The SIAT aPET scanner is composed of 48 detectors organized in 4 rings with each ring containing 12 detectors. Each detector is composed of a 23 × 23 crystal array dual-ended read out by two 8 × 8 silicon photomultiplier arrays with resistor network circuits. In this work, a specific method was proposed to identify the single interaction (non-ICS) and ICS events (both interactions are undergoing ICS). A point source, two hot rod phantoms and a NEMA image quality (IQ) phantom were scanned and images were reconstructed using different types of events.The average full width at half maximum spatial resolutions of the point source obtained with all, non-ICS and ICS events are 0.62 mm, 0.52 mm, and 0.97 mm, respectively. The 1.0 mm diameter rods can be clearly resolved from the images of the ultra-micro hot rod phantom obtained with both all events and only the non-ICS events, but the image obtained with the non-ICS events show a 40% better peak-to-valley ratio for the 1.0 mm rods. The 1.35 mm rods can be clearly resolved from the image obtained with the ICS events. The images of the NEMA IQ phantom showed that the contrast recovery coefficients for hot rods with 1-5 mm diameters were improved by 24% in average, but the signal-to-noise ratio of the uniform region was decreased by 46% with the rejection of the ICS events (at least one-ray undergoing ICS).The results of this work provide useful guidance on whether it is necessary to use detectors that are capable of identifying the ICS events for PET scanners of different spatial resolution.
在当前的正电子发射断层扫描（PET）探测器中，511 keV射线发生晶体间散射（ICS）的概率很高。本研究的目的是研究ICS事件对小动物SIAT aPET扫描仪性能的影响。SIAT aPET扫描仪由48个探测器组成，分为4个环，每个环包含12个探测器。每个探测器由一个23×23的晶体阵列组成，通过两个带有电阻网络电路的8×8硅光电倍增管阵列进行双端读出。在这项工作中，提出了一种特定的方法来识别单次相互作用（非ICS）和ICS事件（两次相互作用均发生ICS）。对一个点源、两个热棒体模和一个NEMA图像质量（IQ）体模进行扫描，并使用不同类型的事件重建图像。使用所有事件、非ICS事件和ICS事件获得的点源的平均半高宽空间分辨率分别为0.62毫米、0.52毫米和0.97毫米。从使用所有事件和仅非ICS事件获得的超微热棒体模图像中可以清楚地分辨出直径为1.0毫米的棒，但使用非ICS事件获得的图像显示，对于1.0毫米的棒，峰谷比提高了40%。从使用ICS事件获得的图像中可以清楚地分辨出直径为1.35毫米的棒。NEMA IQ体模的图像显示，直径为1-5毫米的热棒的对比度恢复系数平均提高了24%，但在剔除ICS事件（至少有一条射线发生ICS）后，均匀区域的信噪比降低了46%。这项工作的结果为不同空间分辨率的PET扫描仪是否有必要使用能够识别ICS事件的探测器提供了有用的指导。
