目的 探讨分次团注双能量扫描 在降低CTU检查辐射剂量的应用价值。方 法 50例行CTU检查的患者平均分两组， 其中试验组(A组)25例，行两次团注对 比剂后实质期常规扫描和排泄期双能量 扫描；对照组(B组)25例，行全泌尿系 平扫及单次团注对比剂后实质期和肾孟 期常规扫描。A组的数据在工作站上使 用双能量后处理软件获得排泄期的最佳 keV图像，将图像的集合系统分段，测量 各段管腔内的CT值．并计算对比噪声比 (contrast to noise ratio, CNR)。B组 排泄期图像发送至同一工作站进行相同 的测量和CNR计算，同时记录所有病例 完成全部检查的有效辐射量((effetive radiation dose，ERD))，比较两组CT 值、CNR、ERD的差别。结果 分次团注 排泄期最佳keV图像集合系统的均匀度 提高，各段CT值均高于常规图像，其差 异有统计学意义(P<0.05)；与常规排 泄期集合系统各段CNR没有统计学意义 (P>0.05)；分次团注双能量方法完成全 部检查的ERD(平均12.56 mSv)明显低于常 规CTU(平均18.27mSv)，差异有统计学意 义(P<0.05)。并能利用双能量软件中的 其他功能为诊断提供更多的信息。结论 分次团注结合双能量扫描能够有效降低 CTU的辐射剂量，提高图像质量。

Objective To discuss the application value of split-bolus injection combined with dual energy CT scan in CT urography. Methods Fifty patients underwent CT urography were randomly and averagely divided into two groups. Twenty-five cases of the experimental group(A group)were applied with conventional scan in parenchymal phase and dual energy scan in excretory phase after split-bolus injection. Other 25 cases of the control group(B group) underwent plain scan in total urinary and conventional scan in parenchymal and excretory phase after single-bolus injection. The keV images of Group A's excretory phase data were acquired by using dual energy software. The images were segmented by urinary collection system and CT values of each lumen were measured, and contract to noise ratio (CNR) was calculated. Images of Group B's excretory phase were sent to the same workstation to do the same measurement and CNR calculation. At the same time, the amount of effective radiation in a complete inspection was recorded for all 50 cases. The CT value, CNR and the amount of effective radiation of two groups were compared. Results The uniformity of excretory phase's keV images of split-bolus injection improves compares to that of conventional method. CT value is significantly higher(P<0.05) while CNR is not significantly different(P>0.05).The effective amount of radiation in a complete inspection(12.56mSv in average)for split-bolus method is lower than conventional one(18.27mSv in average) and it is significantly different(P<0.05). In addition, split-bolus method can also provide more information for diagnosis by using other features in dual energy software. Conclusion Split-bolus injection combined with dual energy scan can effectively reduce the radiation dose of CTU, improve the quality of images.