目的探讨128层螺旋CT全脑灌 注扫描及减半时间低剂量扫描的可行性 和价值。方法 采用随机数字表法将疑 诊为缺血性脑血管疾病或因眩晕症状就 诊的患者分为2组，A组连续动态扫描20 期，总扫描时间30s，共产生20个容积数 据。B组连续动态扫描40期，总扫描时间 60s，共产生40个容积数据。观察2组辐 射剂量和灌注指标。结果 A组容积剂量 指数、剂量程度乘积、有效剂量与B组相 比较均显著降低(P＜0.05)。2组患者尾 状核头、额叶白质、颞枕叶白质CBF、 CBV、MTT水平相比较差异均无统计学意 义(P＞0.05)。2组伪彩图均清晰，可满 足诊断需求。结论 128层螺旋CT减半时 间扫描可显著降低颅脑X线辐射剂量，且 可获得理想的灌注参数，值得进一步研 究探讨。

Objective To investigate the 128 slice spiral CT cerebral perfusion imaging and half low dose scan time of the feasibility and value. Methods The patients whom were suspected of ischemic cerebrovascular disease or symptoms due to vertigo were randomly divided into 2 groups by using the random number table. The 20 phase of continuous dynamic scanning were performed in group A, with total scanning time 30s, and produced a total of the 20 volume data group. The 40 phase of continuous dynamic scanning were performed in group B, with total scanning time 60s, and produced a total of the 40 volume data group. Observe 2 groups of radiation dose and perfusion index. Results The volume dose index, dose rate product and effective dose of group A were significantly lower than those of group B(P<0.05) . There was no significant difference in the levels of CBF, CBV and MTT in the caudate nucleus, frontal lobe white matter and temporal occipital white matter between the 2 groups(P>0.05). The 2 groups of pseudo color images are all clear, which can meet the needs of diagnosis. Conclusion The 128 slice spiral CT half time low dose scan can reduce the radiation dose of the brain significantly, and obtain ideal perfusion parameters, which was worthy of further study.