摘要We implemented a new protocol-multiphase dynamic helical scan to acquire CT angiography (CTA)and whole brain CT perfusion (CTP) images simulta-neously with single scan on 16 multidetector CT (MDCT).A total of 90 patients who were randomly assigned into 3groups were included in our study. Each group underwent CT scan by using the new protocol, traditional CTA and CTP protocol, respectively. The image quality of CTA, the CTP parameter values and the X-ray doses were measured and compared between the new protocol and the traditional protocols. There was no statistically significant difference in the CTA image quality between the above methods (P＝0.55). For CTP parameters, the new protocol tended to overestimate the blood volume (BV) and blood flow (BF)value, and to underestimate the mean transit time (MTT)value compared with the traditional method. However,there was no statistically significant difference in BV, BF,and MTT value between the two methods except permeability surface (PS) (P＞0.05). The volume CT dose index (CTDIvol) and dose length product (DLP) of our protocol were lower than the traditional one. The new protocol can obtain valuable diagnostic information in a shorter time without significant compromise in image quality. In addition, it reduces the radiation dose as well as contrast medium usage on the patient.