NEMA NU 2-2018标准在PET/CT系统性能测试中的作用评价

Evaluation of the effect of NEMA NU 2-2018 Standards in performance test of PET/CT system

目的评价美国国家电器制造协会(National Electrical Manufactures Association,NEMA)最新标准(NU 2-2018)在正电子发射型计算机断层显像/电子计算机断层显像(positron emission tomography/computed tomography,PET/CT)设备性能检测中的作用。方法依据最新的NEMA NU 2-2018标准,检测西门子Biograph Vision PET/CT的空间分辨率、灵敏度、散射分数、计数丢失、随机符合、飞行时间分辨率、计数丢失率和随机符合校正精度、图像质量、衰减和散射校正精度及PET与CT配准精度指标。结果距视野中心1 cm处横向和轴向空间分辨率分别为3.75 mm和3.76 mm;在视野中心和轴向10 cm处的灵敏度分别为16.83 kcps/MBq和16.67 kcps/MBq;放射性浓度为27.37 kBq/mL时,最大等效噪声计数率为258.26 kcps,散射分数为38.58%;系统时间分辨率为209.82 ps;图像质量模型的对比度恢复系数范围为88.9%~96.2%,背景变异系数范围为2.05%~6.80%,平均肺插件残余误差为2.43%;计数丢失和随机符合校正最大误差为3.9%;距离床板末端5 cm和100 cm处,在距视野中心Y轴1 cm处,PET和CT的配准精度分别为0.46 mm和1.07 mm,在距视野中心X轴20 cm处,PET和CT的配准精度分别为1.06 mm和1.45 mm,在距视野中心Y轴20 cm处PET和CT的配准精度分别为0.85 mm和1.15 mm。结论NEMA NU 2-2018标准检测条件更加接近临床,能更好地反映PET/CT设备的系统性能。

Objective To explore the application of National Electrical Manufactures Association(NEMA)NU-22018 Standards in equipment performance testing of positron emission tomography/computed tomography(PET/CT)system.Methods According to NEMA NU 2-2018 Standards,the performance indexes were tested,including the spatial resolution,sensitivity,scatter fraction,count loss,random measurement,timing resolution,count loss rate,random measurement correction accuracy,image quality,accuracy of attenuation and scatter correction,and image co-registration accuracy of Siemens Biograph Vision 600 PET/CT.Results The transverse and axial spatial resolution were 3.75 mm and 3.76 mm at a 1 cm offset,The sensitivity was 16.8 kcps/MBq at the center of the field of view and 16.7 kcps/MBq at a 10 cm offset from the axial of the field of view.The scatter fraction was measured at 38.58%while noise equivalent count rate peaked at 258.26 kcps corresponding to 27.37 kBq/mL.The result of timing resolution is 209.82ps.The contrast recovery of the image quality phantom ranged from 88.9%to 96.2%,and the background variability ranged from 2.05%to 6.80%,the average lung residual error was 2.43%.The maximum error of counting loss and random coincidence correction was 3.9%.At 5 cm and 100 cm from the end of the bed plate,Co-registration accuracy between PET and CT were 0.46 mm and 1.07 mm at a 1 cm offset from the Y of the center field of view,1.06 mm and 1.45 mm at a 20 cm offset from the X of the center field of view,and 0.85 mm and 1.15 mm at a 20 cm offset from the Y of the center field of view.Conclusion The conditions of NEMA NU 2-2018 standards are closer to clinical examination and can better reflect the system performance of PET/CT equipment.