泌尿系结石数字断层容积成像参数优化的实验性研究

A study of optimizing parameters for digital tomosynthesis in detection of uroliths

目的探索数字断层融合成像对显示泌尿系结石的最佳成像参数和能够检出结石的最小直径。方法利用数字断层融合成像技术,分别以4组不同的成像参数(0.5、1.0、2.0、4.0 mAs,60、80、100、120 kV,15、25、40、60次曝光,10°、20°、40°、50°球管摆角)对离体泌尿系结石模型进行投照。采用评分的方法,对比同组内成像参数在显示模型中不同大小、不同密度结石能力方面的差异,分析各种参数下数字断层融合成像能够检出结石的最小直径。选取最佳成像参数组合对泌尿系结石患者进行临床应用验证。结果相对于同组的其他成像参数,使用1.0 mAs、100 kV、25次曝光、20°球管摆角数字断层融合图像所得到的结石评分最高(P<0.05),且曝光剂量较低。1.0 mm及0.5 mm高密度小结石在各组成像参数的数字断层融合图像中评分均很低。结论 1.0 mAs、100 kV、25次曝光、20°球管摆角是数字断层融合技术检出泌尿系结石的最合适成像参数,但对于1.0 mm以下结石,数字断层融合成像检出能力不足。

Objective To study the best imaging parameters of digital tomosynthesis in detection of uroliths and the smallest diameter of the imaging calculi. Methods By using digital tomosynthesis, a in vitro model of uroliths was projected based on 4 differ- ent groups of imaging parameters （0.5, 1.0, 2.0, 4.0 mAs; 60, 80, 100, 120 kV; 15, 25, 40, 60 projections; 10°, 20°, 40° , 50° sweep angle）. With calculi scoring method, the difference in capability of showing various urinary tract calculi within each group of imaging parameters was compared, and the smallest diameter of urolith by digital tomosynthesis was detected. The best imaging pa- rameters will be integrated to estimate the capability of digital tomosynthesis in detection of clinical urolithiasis. Results Compared with the calculus scores from the other imaging parameters within the same group, the calculus scores based on 1.0 mAs, 100 kV, 25 projections and 20° sweep angle were the highest score （ all P 〈 0.05 ） , and the corresponding exposure dose was also lower. The scores of the 1.0 mm and 0.5 mm calculi in all images of digital tomosynthesis were low. Conclusions The 1.0 mAs, 100 kV, 25 projections and 20° sweep angle may be most appropriate imaging parameters for digital tomosynthesis in detection of uroliths. Howev- er, the capability of digital tomosynthesis is insufficient in detecting those urinary tract calculi less than 1.0 mm in diameter.