目的：探讨颈动脉CTA扫描时通过降低管电压以达到降低辐射剂量的可行性。方法：将40例需行颈动脉CTA检查的患者依据管电压不同而分为A（120 kV）、B（80 kV）两组，每组20例。分析比较两组图像的CT值、对比噪声比（CNR）、信号噪声比（SNR）及辐射剂量，并对重建图像质量、血管边缘形态进行评估分析。结果：B组容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP）及有效剂量（ED）较A组分别降低63.97%、63.83%及63.79%，图像质量评价结果：B组颈动脉平均CT值较A组显著增加，差异具有统计学意义（P<0.05）。A、B两组CNR、SNR值组间比较及两两比较差异均无显著统计学意义（P>0.05）；且A、B两组颈动脉重建图像质量、血管边缘形态整体满意，无明显差别（P>0.05）。结论：80 kV低管电压颈动脉CTA扫描在不影响图像质量的前提下，最大能够降低约64%的辐射剂量。因此，颈动脉CTA检查通过降低管电压的低剂量扫描是可行的，可常规使用。%Objective:To explore the carotid artery CTA scan through lower tube voltage in order to achieve the feasibility of reducing radiation dose. Method:40 patients of required carotid artery CTA examination were divided into two groups:according to the tube voltage A(120 kV),B(80 kV),20 cases in each group. Analysed and compared two sets of image CT value,contrast to noise ratio(CNR),signal to noise ratio(SNR)and radiation dose,meantime evaluated the reconstructed image quality,vascular morphology. Result:The CT dose index(CTDIvol),dose length product(DLP)and the effective dose(ED)in group B were lower than in group A 63.97%,63.83%and 63.97%. The results of image quality evaluation:the mean CT value of group B was significantly higher than group A;The difference had statistical significance(P<0.05). The difference of CNR,SNR hadn’t statistical significant(P>0.05). And two groups’ carotid reconstruction image quality,blood vessels,marginal form the overall satisfaction,no significant difference (P>0.05).Conclusion:Using low tube voltage(80 kV)can lower 64%radiation dose.It is proved to be effective and feasible in carotid CT angiography.
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