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目的探讨多层螺旋CT颈部血管造影(CTA)低剂量扫描的可行性和合理性。资料与方法将常规行颈部CTA检查的患者60例随机分为A、B、C三组,每组20例。在其他扫描参数不变的情况下,A组采用常规剂量250 mAs、B组采用150 mAs、C组采用100 mAs条件行CTA扫描。以图像显示解剖结构及病变的情况为主要指标,比较B、C两种低剂量组扫描所得图像质量与常规剂量A组扫描图像质量的差异。结果当mA值由常规250mAs降低至150 mAs和100 mAs时,CT剂量加权指数(CTDI)由16.7 mGy分别降至10.0 mGy和6.7 mGy,下降40.1%和59.8%;剂量长度积(DLP)由(564.6±32.5)mGy分别降至(336.2±24.5)mGy和(204.3±33.7)mGy,下降40.5%和63.8%。B、C组与A组比较,剂量差异均有统计学意义(P<0.01);而B组图像质量与A组比较,差异无统计学意义(P>0.05);C组图像质量与A组比较,差异有统计学意义(P<0.05)。结论150 mAs可作为颈部CTA低剂量扫描的最佳mA值,适当降低管电流是一种切实可行的降低辐射剂量的CTA扫描方法。
Objective To investigate the feasibility and rationality of low-dose CT scanning with multi-slice spiral CT. Materials and Methods 60 cases with routine CTA examination of neck were randomly divided into three groups (A, B and C), 20 cases in each group. Under the condition of other scanning parameters, group A received conventional dose of 250 mAs, group B used 150 mAs, and group C used 100 mAs of CTA. The anatomical structure and lesion status were taken as the main indexes to compare the difference between the scanned image quality of group B and C and the scan group A of conventional dose. Results CT dose weighted index (CTDI) decreased from 16.7 mGy to 10.0 mGy and 6.7 mGy, decreased by 40.1% and 59.8%, respectively, when the mA value decreased from 250 mAs to 150 mAs and 100 mAs. The dose-length product (DLP) 564.6 ± 32.5) mGy decreased to (336.2 ± 24.5) mGy and (204.3 ± 33.7) mGy, decreased by 40.5% and 63.8% respectively. There were significant differences in dose between group B and group C and group A (P <0.01), but there was no significant difference between group B and group A (P> 0.05) A group, the difference was statistically significant (P <0.05). Conclusion 150 mAs can be used as the optimal mA for low-dose CTA in the neck. Appropriate reduction of tube current is a feasible CTA scanning method for reducing radiation dose.