大孔径CT模拟定位机扫描条件对CT值影响分析

Analysis of the effect of scanning conditions of Brilliance CT Big Bore on CT value

目的:分析大孔径CT模拟定位机扫描条件对CT值的影响,为模拟定位工作中不同扫描条件的选择提供参考。方法:采用飞利浦大孔径CT模拟定位机扫描CIRS-062M电子密度模体并建立CT值-相对电子密度曲线。分析管电流、管电压、层厚、层间距、分辨率、准直器、旋转时间、重建模型、过滤器、几何位置多种扫描条件对CT值的影响。结果:管电压变化对CT值影响最为显著,90 kV、140 kV管电压CT值平均偏差66.1 HU、-24.0 HU,差异主要集中在高密度区域。过滤器YA、YB对CT值影响明显,CT值平均偏差-40.7 HU、-39.9 HU。不同扫描位置对CT值有一定影响。结论:管电压、部分过滤器、扫描位置对CT值的影响不可忽略,临床工作中需规范上述参数的使用,以免造成剂量计算偏差。

Objective:To analyze the impact of the scanning conditions of Brilliance CT Big Bore on CT value,and provide a reference for the selection of different scanning conditions in the simulation positioning work.Methods:The Philips Brilliance CT Big Bore was used to scan the CIRS-062M electron density phantom and establish the CT value-electron density curve.The effects of tube current,tube voltage,thickness,increment,resolution,collimator,rotation time,reconstruction,filter,geometric position on the CT value were analyzed.Results:The tube voltage change had the most significant effect on the CT value.The average deviation of the CT value of the 90 kV and 140 kV tube voltage was 66.1 HU and-24.0 HU.The difference was mainly concentrated in the high-density area.The filters YA and YB had a significant effect on the CT value,and the average deviation of CT values was-40.7 HU and-39.9 HU.Different scanning positions had a certain influence on the CT value.Conclusion:The influence of tube voltage,filter and scanning position on the CT value cannot be ignored.In clinical work,the use of the above parameters must be regulated to avoid deviations in dose calculation.