Objective To investigate and find out the best weight Adaptive Statistical Iterative Reconstruction (ASIR) algorithm and low radiation dose in head and neck CTangiography.Methods 100 patients were selected to have head and neck CT angiography combining examination, andrandomly divided them into 5 groups with 20 cases in each group. These patients’ ages and body mass index are almost the same. These 100 patients were scanned by gem energy spectrum CT, with tube voltage of 100 kVp, contrast medium 270 mgI/mL. We keep the other scanning parameters consistent. The images were reconstructed to form signal noise ratio, carrier noise ratio evaluation by adaptive iterative reconstruction technique. But the weight in this technique is different. Percentages are 20%, 40%, 60%, 80% and 100% perspectively. By evaluating the best image quality, doctors choose the best weight ratio of ASIR is 60%. And based on this conclusion, 60 patients in this study were selected in our hospital to conduct CT angiography combining examination, and they were randomly assigned to double low group and double high group with 30 patients in each group. With the other scanning parameters consistent, the double low team uses a tube voltage of 100 kVp, contrast medium 270 mgI/mL, and 60% ASIR technique to reconstruct the image; double high group uses tube voltage of 120 kVp, contrast medium 350 mgI/mL, and filtered back projection to reconstruct image. Finally, the resulting data was statistically analyzed. Results Contrasting noise ratio and signal noise ratio of double low group are significantly higher than those in double high group (P<0.05); the image quality score, carotid artery CT number, image noise number are not significantly different in two group (P>0.05). The radiation dose of double low group is significantly lower than that of the double high group (P<0.05). The average iodine intake dose in double low group is significantly lower than that of the double high group (P<0.05).Conclusion Thegem energy spectrum CT adopts the technology of ASIR combining with a scanning method of low dose low concentration contrast medium. Compared with the traditional head and neck CT angiography examination with high tube voltage, high concentration of contrast medium and filtered back projection reconstruction method, the contrast medium intake and radiation dose of this method is significantly reduced and there has no significant difference in image quality.%目的：探讨最佳权重自适应统计迭代重建（Adaptive Statistical Iterative Reconstruction，ASIR）技术结合低剂量扫描在头颈联合CT血管造影（Computed Tomographic Angiography，CTA）成像的临床应用研究。方法选取我院头颈CTA联合检查的患者100例，随机分为5组，每组20例。年龄、体质指数差异不明显。应用宝石能谱CT设置管电压100 kVp，使用浓度270 mgI/mL对比剂，其余扫描参数一致。5组患者分别使用20%、40%、60%、80%和100%的ASIR对上述得到图像进行重建并进行信噪比（SNR）、对比度噪声比（CNR）及图像质量主观评分，优选出最佳图像质量的ASIR重建权重比为60%。随后依此结论为基础，在我院进行头颈CTA联合检查的患者中选取60例，随机分为双低组和双高组各30例。双低组采用管电压100 kVp管电压，对比剂270 mgI/mL，使用最优权重比60%ASIR技术重建图像；双高组采用120 kVp管电压，对比剂350 mgI/mL，采用滤波反射投影技术（Filtered Back Projection，FBP）重建图像进行头颈CTA检查，其他扫描参数一致。对所得的数据资料进行相应的统计学分析。结果双低组的CNR和SNR显著高于双高组（P<0.05）；两组患者的图像质量评分、颈动脉CT值、图像噪声值比较差异不显著（P>0.05）；双低组的辐射剂量值显著低于双高组（P<0.05）；双低组人均碘摄入剂量显著低于双高组（P<0.05）。结论宝石能谱CT采用ASIR技术结合低剂量低浓度对比剂扫描方法，相比较采用传统高管电压、高浓度对比剂、使用FBP重建方式进行头颈部CTA检查；对比剂的摄入量显著降低、辐射剂量显著降低、图像质量差异不显著。
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