Abstract： Objective To evaluate the application of prospective ECG-gating Flash spiral scan mode dual-source CT in aortography,and compare it's image quality and radiation dose with without ECG-synchronization high-pitch spiral scanning mode.Methods Fifty consecutive patients (Group A) with suspected aortic dissection or after operations for the aortic dissection were scanned with prospective ECG-gated high-pitch scan and another 50 consecutive patients(Group B) were analyzed by non-ECG-gated high-pitch scan.Image quality of the aortic was assessed by two independent readers.Image noise was measured,radiation dose estimates were calculated.The imaging quality of the aortic and the radiation dose were compared with Mann-whitney U and t test.Results The average image quality score [(1.18 ± 0.40) in group A and (1.23 ±0.31) in group B] showed no significant difference between group A and group B(U =1.20,P =0.23).The mean radiation dose of group A was lower than that of group B [(1.49 ± 0.38) mSv in group A,(2.79 ± 0.54) mSv in group B,t =13.677,P ＜ 0.05].Conclusion Prospective ECG-gated dualsource CT Flash spiral scanning with low radiation dose and good image quality in the aortic dissection with high value of clinical application.