中文摘要：

目的探讨70kV管电压结合迭代重建技术在体型中等或偏瘦患者的胸部低剂量扫描中的应用价值．方法：00例胸部CT平扫的检查者随机分成2组，分别采用第二代双源CT70kV管电压结合迭代重建（A组）及100kV管电压滤波反投影重建技术（B组）行胸部CT扫描，测量CT值，图像噪声，计算信噪比（SNR）．图像质量进行5分法评分，计算并比较2组的辐射剂量．结果2组比较，CT值、图像噪声差异有统计学意义（P〈0．05），A组的CT值和图像噪声均较B组增加了约14％，SNR差异无统计学意义（P〉0．05），2组图像质量均能满足诊断的需要，2组的主观图像质量评分比较差异有统计学意义（P〈0．05），B组图像质量要好于A组。且肺窗评分高于纵隔窗，评分均大于3分，病变显示率2组一致．A组CTDIvol、DLP和ED均低于B组（P〈0．05），均降低了50％．结论体型中等或者偏瘦的患者采用70kV管电压联合迭代重建技术，可以在不影响诊断的同时，有效减低辐射剂量．

英文摘要：

Objective To evaluate the application value of 70kV combine iterative reconstruction technique in chest low dose CT for median and low BMI patients. Methods 100 patients were randomly divided into two groups, underwent plain chest CT with 70kV ＋ iterative reconstruction technique （A） and 100kv ＋ filter back projection reconstruction technique （B） , respectively. CT attenuation value and image noise were measured, and SNR was calculated. The image quality was scaled by 5 points, and the irradiation doses of the two groups were compared. Results There were statistically significant differences in CT attenuation value and image noise between the two groups （P 〈 0.05） . CT attenuation value and image noise of group A were increased about 14% compared with group B, but SNR showed no difference between the two groups （P 〉 0.05） . The image qualities of both groups could meet the need of diagnosis, and the subjective image quality scale points were significantly different （P 〈 0.05） . The image quality of group B was better than that of group A, and the lung window setting points were higher than mediastinal window setting in the two groups, and were greater than 3 points. The lesion detection was comparable. CTDIvol, DLP and ED of group A were lower than group B by 50%. Conclusion Chest CT with 70kV＋ iterative reconstruction technique in median and low BMI patients showed decreased radiation dose while the image quality remained acceptable.