SPECT/PET系统模型试验技术探讨

Investigation on Test Technique of SPECT/PET System Model

目的探讨SPECT/PET系统模型的试验技术。方法首先对仪器基本性能进行测试,然后使用99mTc灌注SPECT/PET模型,使之产生30kc/s的计数。低能高分辨率准直器,128×128矩阵,Zoom1.0,360°采集,每帧6°,最小旋转半径,按前位500k所用时间采集模型图像。经过不同Butterworth截止频率(fc)的图像重建,肉眼观察和半定量分析影像质量。结果图像均匀断面无明显环形伪影,线性插件区无明显弯曲伪影。最佳图像信息密度859.93,fc为0.4Hz,能够分辨的最小冷和热灶的直径分别为9.2mm和14.3mm,11.4mm冷灶的对比度为17.52%。结论对于灌注99mTc的SPECT/PET模型,使用优化的采集条件,根据信息密度选择合适的滤波参数,可以得到更好的图像。

Objective To investigate the test technology of SPECT/PET system model. Methods Basic performance of SPECT was first measured and then filled SPECT/PET phantom with ^99mTc solution in order to have count of 30kc/s for two detectors.Acquired images with LEHR collimators and the minimum possible rotation radius for both detector, matrix 128×128, Zoom 1.0, stopped on time per projection according to time of per anterior static image for 500k. Reconstruction was performed using several fc： 0.3, 0.4, 0.5 and 0.6 respectively. The qualities of transverse slice images were evaluated by visual reading and semi-quantitative analyzing. Results The transverse slices of uniform activity region were no obvious circle artifacts and line insert regions were no distortion. Information densities of uniform activity region for the best images were 859.93, fc was 0.4, distinguishable the smallest diameter of cold and hot lesions was 9.2mm and 14.3 mm respectively, contrast of cold lesions in diameter of 11.4 mm was 17.52%. Conclusion For SPECT/PET phantom filled with ^99mTc, using optimized acquisition conditions and choosing appreciated filter parameters according to the value of information density can obtain the best images.