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目的：比较在头颅CT动脉造影（CTA）成像中，双源CT的大螺距Flash模式与双能模式（DECT）在成像质量，辐射剂量方面有无区别。方法从2012年8月～2013年1月疑似颅内动脉瘤109例患者中，选出两组不同检查模式的病例，每组20例。两名医师对图像质量进行5级评分，同时比较两组的CT容积剂量指数（CTDIvol）、剂量长度乘积（DLP）。结果 Flash组和DECT组扫描模式的CTDIvol、DLP分别为：30.17±1.74mGy，697.14±38.23mGy?cm；13.52±0.58mGy，289.92±16.56mGy?cm。两组间颅内血管的图像质量无明显差异（Z=-0.403，P=0.715）。颅底血管的椎基底动脉无统计学差异（Z=-1.286，P=0.12），而颈内动脉C2-C5段图像质量DECT组明显低于Flash组（Z=-6.273，P＜0.001）。结论两种模式的图像质量在颅内血管和颅底椎基底动脉上无明显差异；对于颅底颈内C2-C5段，Flash模式明显优于DECT模式。Flash模式的辐射剂量要大于DECT模式。“,”Objective To compare radiation dose and image quality of different protocols for cerebral CTA:high-pitch lfash mode,DECT mode.Methods We retrospectively assembled two cohorts from 109 patients who underwent cerebral CTA from August 2012 to January 2013 with different protocol,each containing 20 patients. Two radiologists assessed image quality with 5-piont scale subjectively.Radiation dose parameters(CTDIvol,DLP) were compared.Results Mean CTDIvol,DLP were Flash mode 30.17±1.74mGy,697.14±38.23mGy?cm,DECT mode 13.52±0.58mGy,and 289.92±16.56mGy?cm.Image quality of intracranial vessels indicate no difference between groups(Z=-0.403,P=0.715);vertebral artery and basilar artery show no difference between groups too(Z=-1.286,P=0.12).Image quality of internal carotid artery(C2-C5) in Flash is superior to DECT(Z=-6.273,P<0.001). Conclusion Compared with Flash mode,DECT mode has the same good image quality for vertebral artery,basilar artery and intracranial vessels;however image quality of internal carotid artery(C2-C5) is worse.Radiation dose was signiifcantly lower with DECT mode.