目的 通过模体实验探究第三代双源CT不同能量组合对物质电子密度/有效原子序数（Electron Density/Effective Atomic Number，Rho/Z）检测的准确性与重复性误差，为临床应用提供准确指导。方法 使用西门子SOMATOM Force CT不 同双能量组合对Catphan 600标准模体的CTP404模块进行扫描。并通过syngo.via工作站测量不同能量组合的Rho/Z和CT值。 并记录每次扫描的容积CT剂量指数和剂量长度乘积。各组数均进行组内一致性检验，单独样本t检验。并对所有参数进行 优劣解距离法（Technique for Order Preference by Similarity to an ideal Solution，TOPSIS）综合分析。结果 五种双能量组合 下，Rho/Z和CT值组内测量一致性较高。经单独样本t检验，电子密度测量值与实际值有明显差异（P<0.05）的占90%， 无明显差异（P>0.05）的情况占10%丨有效原子序数测量值与实际值有明显差别（P<0.05）的情况占48.6%，无明显差异 （P>0.05）的情况占51.4%。TOPSIS分析得出80/Sn150 kV组为最优组合。结论 80/Sn150 kV组既可以保证测量的准确度， 又可以最大限度地缩减辐射剂量，值得应用推广。

Objective To explore the accuracy and repeatability error of the detection of electron density/effective atomic number (Rho/Z) by different energy combinations of the third-generation dual-source CT, so as to provide accurate guidance for clinical application. Methods The CTP404 module of Catphan 600 standard module was scanned with different dual-energy combinations of Siemens SOMATOM Force CT. Rho/Z and CT values of different energy combinations were measured through syngo.via workstation. Volumetric CT dose index and dose length product for each scan were recorded. Intra-group consistency test was performed for each group, and t-test was performed for individual samples. Technique for order preference by similarity to an ideal solution (TOPSIS) comprehensive analysis of all parameters was also carried out. Results The consistency of the Rho/Z and CT values was higher in the five dual-energy combinations. By the t-test of individual samples, 90% of the measured values of electron density were significantly different from the actual values (P<0.05), and 10% were not significantly different (P>0.05). 48.6% of the measured values of effective atomic number were significantly different from the actual value (P<0.05), and 51.4% had no significant difference (P>0.05). TOPSIS analysis showed that 80/Sn150 kV group was the optimal combination. Conclusion The 80/Sn150 kV group can not only ensure the accuracy of measurement, but also reduce the radiation dose to the greatest extent, which is worthy of application and promotion.