能谱CT低管电压对下肢血管成像图像质量及辐射剂量影响

Feasibility of low tube voltage protocol in lower extremity artery angiography with gemstone detectors CT

目的:探讨能谱CT低管电压技术对下肢动脉成像图像质量及辐射剂量的影响。方法:将72例行下肢CT血管成像(CTA)的患者随机分为A、B、C三组,三组管电压分别为120kV、100kV及80kV,其余扫描参数保持一致。根据原始图像和最大密度投影(MIP)重组图像对三组下肢动脉图像质量进行评分,测量血管CT值、信噪比(SNR)、对比信噪比(CNR)及患者所接受的辐射剂量。结果:1三组图像血管CT值C组最高,A组最低,三组间差异有统计学意义(P<0.05),图像CNR、SNR组间差异无统计学意义(P>0.05);2辐射剂量C组最低,A组最高。与A组相比,B、C组CT剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(ED)分别降低35.8%、34.9%、34.4%及65.8%、64.4%、64.4%,差异均具有统计学意义(P<0.05)。结论:能谱CT下肢血管成像使用低管电压扫描可满足临床诊断需求,且可大大降低患者所接受的辐射剂量。

Objective：To evaluate the feasibility of low tube voltage protocol for lower peripheral artery CTA using gemstone detectors CT.Methods：Totally 72 patients who were randomly divided in three groups（group A,B,C）,underwent lower extremity CTA,the tube voltage as 120 kV,100kV,80 kV was used respectively,keeping the same tube current of 200 mAs.Other scanning parameters were kept identically.Contrast medium was injected automatically with bolu s tracking respectively.Image quality,segmental vascular enhancement,signal tonoise ratio（SNR）,contrast to noise（CNR）and effective dose（ED）were independently evaluated in these 3 groups.Results① There was no significant difference of image quality of these 3groups.②The CT values of artey in group C was the highest and that in group A was the lowest There were statistical differences among three groups（P〈0.05）.Statistics showed there was no significant differences in SNR and CNR among the three groups（P〉0.05）.③Compared with group A,the CT DIvol,DLP and ED were reduced by35.8%,34.9%,34.4%respectively in group B and reduced by 65.8%,64.4%,64.4%respectively in group C.Conclusion：The tube voltage can be lowered from 120 kV to 80 kV for lower extremity CTA,in order to reduce the radiation dose,meanwhile the image quality and diagnostic confidence could be maintained.