Gemini PET/CT系统性能模型测试

Phantom study for the systemic performance of Gemini PET/CT

目的 探讨GeminiPET CT系统性能的评价方法和指标。方法 选用插件直径较小的Jaszczak模型 ,加入初始活度为 83.10 2MBq的1 8F 脱氧葡萄糖 (FDG) ,分别在全身和脑显像方式下 ,以X线CT作衰减校正 (CTAC) ,测量PET CT对模型冷、热区图像的分辨能力 ;选用Philips圆柱体空心模型 ,分别用CTAC和1 37Cs作衰减校正 (CsAC) ,测量标准摄取值 (SUV)和均匀性 ;将 4颗2 2 Na固体点源置于检查床床垫下 ,与患者的数据同步采集以评价PET与CT图像匹配的准确度。全部采用临床显像方式重建图像。结果 全身显像方式可分辨出模型中直径 6 .4mm的冷、热区 ;脑显像方式可分辨出直径 4 .8mm的冷、热区。用CTAC和CsAC测量的SUV分别为 0 .92± 0 .2 4和 0 .99± 0 .2 6。目测观察分别由CTAC和CsAC的图像均匀性良好 ,两者像素平均计数分别为 2 5. 812 3± 72 .839和 2 75 8.19±838.79。目测观察图像匹配效果良好。结论 该方法和指标可用于评价该PET CT的系统性能和常规质量保证。

Objective To develop the methods and parameters for evaluating the systemic performance of Gemini PET/CT. Methods The spatial resolution, standardized uptake value (SUV),uniformity and accuracy of image registration were selected as the evaluating indexes. The Jaszczak phantom with smaller inserts was filled with 18F-fluorodeoxyglucose (FDG) solution and imaged with whole body and brain imaging modes, respectively, to evaluate the spatial resolution of the PET/CT; a Philips hollow phantom was filled with 18F-FDG solution and imaged for calculating the SUV and the uniformity parameters; four 22Na solid sources were put under the pad of the patient table and imaged synchronously with the patient's data acquisition to evaluate the accuracy of the PET and CT image fusion. Results The rods of the diameter of 6.4 mm of both the hot and cold inserts were observed with whole body imaging mode, and rods of the diameters of 4.8 mm of both the hot and cold inserts were observed with brain imaging mode. The SUV with X-ray CT attenuation correction (CTAC) was 0.92±0.24, and was 0.99±0.26 with 137Cs attenuation correction (CsAC), and t=-1.327, P>0.05 between the two groups. The uniformity of the images with both CTAC and CsAC was very nice, no artifacts were seen either. The maximum pixel counts was 3790, the minimum was 1434, the average was 2581.23 and the standard deviation was 728.39 with CTAC; and were 4218, 1073, 2758.19 and 838.79 with CsAC correspondingly, and t=-1.069, P>0.05 between the two groups. The images of PET and CT were registrated better, and also no diversity was detected on the fusion images. Conclusions These methods and parameters might be used to evaluate the systemic performance of the PET/CT, and could also be used as the supplementary items for the acceptance test and daily quality assurance of the PET/CT.