多参数设置对低剂量胸部CT扫描图像质量及辐射剂量的影响

摘要

目的 探讨当iCT管电流设置为17 mAs时,其他参数设置对低剂量胸部CT扫描图像质量及辐射剂量的影响.方法 选取低剂量胸部CT筛查的200名志愿者,设定管电流为17 mAs,根据管电压及自动曝光控制(DoseRight)设置分为4组:A组为120 kV,DoseRight扫描;B组为100 kV,DoseRight扫描;C组为120 kV,固定管电流扫描;D组为100 kV,固定管电流扫描.对所有扫描图像分别采用混合迭代重建(iDose4)和全模型迭代重建(IMR)进行肺窗及纵隔窗算法重建.比较4组的有效剂量及图像质量.结果 4组肺窗、纵隔窗的iDose4、IMR重建图像质量评分及有效剂量差异均有统计学意义;A、B组图像质量均较C组图像质量好(P均＜0.05),与其余3组比较D组图像质量最差(P均＜0.05);C组纵隔窗及D组肺窗、纵隔窗的iDose4重建图像质量评分较低;A、B、C、D组SNR值依次降低(P均＜o.01);A组有效剂量最高(P均＜0.01),D组有效剂量最低(P均＜0.01),B组和C组间有效剂量差异无统计学意义(P=0.055).结论iCT管电流为17 mAs时,采用100 kV管电压、DoseRight扫描及IMR重建方式可获得较满意的图像质量和较低的辐射剂量.%Objective To investigate the impact of parameters setting on image quality and radiation dose of low-dose chest CT scanning when iCT tube current was set as 17 mAs.Methods Two hundred volunteers who accepted low-dose chest CT screening with tube current was set as 17 mAs were randomly divided into four groups according to the tube voltage and automatic exposure control (DoseRight) settings (group A:120 kV,DoseRight;group B:100 kV,DoseRight;group C:120 kV,fixed tube current;group D:100 kV,fixed tube current).Then hybrid iterative reconstruction (HIR:iDose4) and iterative model reconstruction (IMR) were performed on all scanned images of lung and mediastinal window algorithm,respectively.The effective dose and image quality of 4 groups were compared.Results There were significant differences of image quality score and effective dose among 4 groups.The image quality of group A and B were better than that of group C (P＜0.05),and of group D was the worst compared with the other three groups (P＜0.05).Image quality scores of the mediastinal window of group C and D and the lung window of group D at iDose4 reconstruction were lower.SNR value of group A,B,C,D decreased in order (P＜0.01).Group A had the highest effective dose (P＜0.01),while the effective dose of group B and group C had no significant difference (P=0.055),and group D had the lowest effective dose (P＜ 0.01).Conclusion When tube current was set as 17mAs at iCT,selecting 100 kV tube voltage,DoseRight and IMR reconstruction arithmetic can obtain satisfactory image quality and low radiation dose.