Ko Guen Bae, Kim Kyeong Yun, Yoon Hyun Suk, Lee Min Sun, Son Jeong-Whan, Im Hyung-Jun, Lee Jae Sung
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea.
Med Phys. 2016 Jan;43(1):72. doi: 10.1118/1.4937784.
In this study, the authors present a silicon photomultiplier (SiPM)-based positron emission tomography (PET) insert dedicated to small animal imaging with high system performance and robustness to temperature change.
The insert consists of 64 LYSO-SiPM detector blocks arranged in 4 rings of 16 detector blocks to yield a ring diameter of 64 mm and axial field of view of 55 mm. Each detector block consists of a 9 × 9 array of LYSO crystals (1.2 × 1.2 × 10 mm(3)) and a monolithic 4 × 4 SiPM array. The temperature of each monolithic SiPM is monitored, and the proper bias voltage is applied according to the temperature reading in real time to maintain uniform performance. The performance of this PET insert was characterized using National Electrical Manufacturers Association NU 4-2008 standards, and its feasibility was evaluated through in vivo mouse imaging studies.
The PET insert had a peak sensitivity of 3.4% and volumetric spatial resolutions of 1.92 (filtered back projection) and 0.53 (ordered subset expectation maximization) mm(3) at center. The peak noise equivalent count rate and scatter fraction were 42.4 kcps at 15.08 MBq and 16.5%, respectively. By applying the real-time bias voltage adjustment, an energy resolution of 14.2% ± 0.3% was maintained and the count rate varied ≤1.2%, despite severe temperature changes (10-30 °C). The mouse imaging studies demonstrate that this PET insert can produce high-quality images useful for imaging studies on the small animals.
The developed MR-compatible PET insert is designed for insertion into a narrow-bore magnetic resonance imaging scanner, and it provides excellent imaging performance for PET/MR preclinical studies.
在本研究中，作者展示了一种基于硅光电倍增管（SiPM）的正电子发射断层扫描（PET）插入件，其专为小动物成像设计，具有高系统性能以及对温度变化的强耐受性。
该插入件由64个LYSO-SiPM探测器模块组成，排列成4个环，每个环有16个探测器模块，形成64毫米的环直径和55毫米的轴向视野。每个探测器模块由一个9×9的LYSO晶体阵列（1.2×1.2×10毫米³）和一个单片4×4 SiPM阵列组成。监测每个单片SiPM的温度，并根据实时温度读数施加适当的偏置电压，以保持性能均匀。使用美国国家电气制造商协会NU 4-2008标准对该PET插入件的性能进行表征，并通过体内小鼠成像研究评估其可行性。
该PET插入件的峰值灵敏度为3.4%，中心处的体积空间分辨率为1.92（滤波反投影）和0.53（有序子集期望最大化）毫米³。在15.08 MBq时，峰值噪声等效计数率和散射分数分别为42.4 kcps和16.5%。通过应用实时偏置电压调整，尽管温度剧烈变化（10 - 30°C），仍保持了14.2%±0.3%的能量分辨率，计数率变化≤1.2%。小鼠成像研究表明，该PET插入件可以产生高质量的图像，对小动物成像研究有用。
所开发的与磁共振兼容的PET插入件设计用于插入窄孔磁共振成像扫描仪中，并为PET/MR临床前研究提供了出色的成像性能。
