不同双能量组合对Rho/Z检测准确性的模体研究

Phantom Study on the Accuracy of Rho/Z Detection with Different Dual Energy Combinations

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%;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.