自动管电流调节技术在胸部低剂量CT筛查中的临床价值

Clinical value of automatic tube current modulation in chest screening with low dose CT

目的探讨16层螺旋CT自动管电流调节(ATCM)技术在胸部低剂量CT筛查中的临床价值。方法 94名常规体检人员分为两组:A组45名,扫描方案为固定噪声指数(NI)为14,应用ATCM技术自动调节管电流(20～200mA);B组49名,扫描方案为固定管电流40mAs。两名医师采用双盲法对肺尖、中肺、下肺图像进行图像质量评分(IQS),测量图像标准差(SD)值,记录加权CT剂量指数(CTDIw),并进行统计学分析。结果肺尖、中肺、下肺SD值:A组为13.62±2.07、11.70±0.85、11.89±1.26,B组为17.20±2.66、11.29±2.32、12.82±2.49;IQS:A组为1.82±0.36、1.58±0.38、1.66±0.34,B组为2.30±0.47、1.67±0.42、1.74±0.48。在肺尖,A组的SD值和IQS低于B组(P<0.05)。A、B两组CTDIw比较:受检者体质量指数(BMI)≤27kg/m2时,A、B两组差异无统计学意义;BMI>27kg/m2时,A组高于B组(P<0.05)。结论胸部低剂量CT筛查中,应用ATCM技术可在更大的密度衰减范围和体质量较大的人群中得到更高质量的图像。

Objective To investigate the clinical value of automatic tube current modulation（ATCM）in low dose chest scaning with 16-slice spiral CT.Methods Ninety-four healthy subjects for routine health examination were enrolled in this study and divided into two groups.Forty-five subjects of group A underwent chest CT scanning using ATCM（20—200 mA）with noise index（NI）of 14,and 49 subjects of group B underwent chest CT scanning with a fixed tube current of 40 mAs.CT images were analyzed by two radiologists with double blind method.Image quality scores（IQS）of lung apex,middle lung and lower lung were made,the image standard deviation（SD）was measured,and the weighted CT dose index（CTDIw）was also recorded.The statistical analysis was performed.Results SD values in lung apex,middle and lower lungs was 13.62±2.07,11.70±0.85,11.89±1.26 in group A,and 17.20±2.66,11.29±2.32,12.82±2.49 in group B,as well as the corresponding IQS of these three sites were 1.82±0.36,1.58±0.38,1.66±0.34 in group A,and 2.30±0.47,1.67±0.42,1.74±0.48 in group B,respectively.SD value and IQS of group A were lower than those of group B in lung apex（P〈0.05）.For the subjects with body mass index（BMI）≤27 kg/m^2,there was no statistical difference of CTDIw between the two groups（P〉0.05）.When BMI27 kg/m^2,CTDIw of group A was higher than that of group B（P〈0.05）.Conclusion The application of ATCM in low dose chest CT screening could provide more homogeneous images with better image quality and more attenuation areas in obese subjects.