自动管电流调节技术对主动脉夹层术后的评价及其辐射剂量的研究

目的探讨64排螺旋CT(MSCT),采用固定噪声指数(NI)的Z轴自动管电流调节(ATCM)技术在主动脉夹层术后CT造影中对图像质量及辐射剂量的影响。资料与方法随机将本院主动脉夹层术后的患者100例分为2组,每组50例。A组采用固定管电流扫描技术,均采用280 mA。B组采用Z轴ATCM扫描技术,管电流为100～350 mA,根据体重指数(BMI)不同分为两组:BMI>25 kg/m2者,NI=10;BMI<25 kg/m2者,NI=12,其余扫描参数均一致。将所有图像均传输至ADW 4.3工作站,进行三维及二维后处理,同时记录机器自动生成的CT剂量指数(CTDlvol)、相应剂量长度乘积(DLP)。结果 B组在不影响诊断的情况下,辐射剂量较A组CTDlvol降低了28.3%、DLP降低了30.4%。A组CTDIvol均值为(19.13±1.94)mGy;DLP均值为(1205.59±197.12)mGy.cm,B组BMI>25 kg/m2者CTDIvol均值为(14.82±2.97)mGy;DLP均值为(887.6±177.51)mGy.cm,BMI<25kg/m2者CTDIvol均值为(12.61±2.17)mGy;DLP均值为(789.86±139.33)mGy.cm,所有图像均能满足诊断需要。结论 64排螺旋CT采用固定NI的ATCM技术在主动脉夹层CT造影中可获得较好图像质量,在满足诊断需求的同时降低了患者辐射剂量。

Automatic Tube Current Regulation Technique for the Evaluation of Aortic Dissection and Postoperative Radiation Dose

Objective To discuss the effect on image quality using a fixed noise figure of Z axis automatic tube current regulation technique in CT angiography of aortic dissection,and reduce radiation dose.Materials and Methods 100 patients with aortic dissection were randomly divided into 2 groups.Group A with fixed tube current scanning technique,tube current 280 mA.Group B,Z axis automatic tube current regulation scanning technique,tube current 100 ～ 350 mA,who were divided into two groups according to BMI,BMI> 25 Kg/m2,NI = 10;BMI <25Kg/m2,NI = 12,the other scan parameters were the same.All images were transferred to ADW 4.3 workstation,three dimensional and two dimensional post processing,and machine automatically generated CT dose index(CTDlvol),the corresponding dose length product DLP were recorded.Results Group B did not affect the diagnosis,the radiation dose compared with group A CTDlvol reduced 28.3%,DLP reduced by 30.4%.Mean CTDIvol of group A was(19.13 ± 1.94) mGy;mean DLP was(1205.59 ± 197.12) mGy·cm.In group B BMI> 25 Kg/m2,mean CTDIvol was(14.82 ± 2.97) mGy;mean DLP was(887.6 ± 177.51) mGy·cm.In group BMI <25Kg/m2,mean CTDIvol was(12.61 ± 2.17) mGy;mean DLP was(789.86 ± 139.33) mGy·cm,all images were qualified to the diagnostic needs.Conclusion 64 slice spiral CT with a fixed noise index of automatic tube current regulation techniques in CT angiography of aortic dissection can obtain better image quality,and also reduce the radiation dose.