目的 探讨低浓度对比剂结合低 管电压的“双低”模式行320排CT头颈部 动脉成像的图像质量和辐射剂量。方法 60例行头颈部CTA患者随机分为两组：A组 30例，使用120kV管电压，优维显370mgI/ mL对比剂；B组30例，采用100 kV管电 压，碘克沙醇270mgI/mL对比剂，余参数 设置相同。测量两组患者头颈动脉的CT 值、背景CT值及噪声值，计算对比噪声 比；记录设备自动生成的剂量长度乘积， 计算有效剂量。应用独立样本的t检验对 上述数据进行统计学分析。结果 两组图 像质量均满足临床诊断要求，头颈部动脉 的CT值、对比噪声比差异无统计学意义(P ＞0.05)。A组剂量长度乘积和有效剂量高 于B组，差异有统计学意义(P＜0.05)。结 论 “双低”技术结合迭代重建行320排CT 头颈部动脉成像，图像质量能满足临床诊 断要求，且有效地降低了辐射剂量。

Objective To evaluate image quality and radiation dose under low concentration of contrast agent and low tube voltage for head and neck CTA by using of 320-row CT with a "double low" scanning protocol. Methods 60 patients, who underwent head and neck CTA with a 320-row CT scanner, were divided into two groups randomly. 30 patients (group A) received 120 kV voltage and ultravist (370mgI/ml), and the remaining 30 patients (group B) received 100 kV voltage and iodixanol (270mgI/ml). CT values, standard deviation of intracranial arteries and image noise on the corona radiate were measured to calculate contrast-noise-ratio(CNR).Then recorded dose length product and calculated the effective radiation dose. The above all data used two independent sample t test for statistical analysis. Results Image quality of two groups were conform to the requirements of diagnosis. The CT value and CNR of head and neck artery had no significant difference between two groups(P＞0.05).The dose length product and the effective radiation dose of group A were higher than group B, and there were statistically significant difference between them(P＜0.05). Conclusion Image quality of head and neck CTA by the scanning protocol (100kV+iodixanol) of 320-row CT scanner can meet the requirement of clinical diagnosis, and effectively reduce the radiation dose.