目的：探讨新型冠状病毒肺炎疫情期间,采用不同管电压、管电流扫描方案联合KARL迭代重建行胸部CT筛查的应用效果。方法：在2020年2月10日至2020年2月15日期间,前瞻性收集我院发热门诊因新型冠状病毒肺炎筛查需要行胸部CT平扫的120例受检者,随机分为A、B、C、D 4组（n=30）,按照不同扫描方案进行胸部CT检查。A组采用管电压120 kV,有效管电流60 mAs,激活管电流自动调制;B组采用管电压120 kV,固定管电流30 mA;C组采用管电压100 kV,有效管电流60 mAs,激活管电流自动调制;D组采用管电压100 kV,固定管电流30 mA。扫描完成后,对各组CT数据均采用滤波反投影（filtered back projection,FBP）算法和KARL迭代重建2种模式进行图像重建,测量、记录各组图像感兴趣区域的图像噪声值,并基于图像噪声、图像伪影及图像总体质量三方面进行主观评分,计算各组胸部CT扫描的辐射有效剂量。采用单因素方差分析及配对t检验比较各组间同种重建图像及不同组中同种图像重建方法时的图像噪声值及辐射有效剂量;分别采用Kruskal-Wallis检验及Wilcoxon检验比较各组图像及同组不同图像重建方法下的图像主观评分。结果：采用不同扫描方案的A、B、C、D组,受检者行胸部CT检查接受的辐射有效剂量分别为（2.5±0.4） mSv、（1.2±0.1） mSv、（1.6±0.2） mSv及（0.8±0.1） mSv,降低管电压和管电流均能明显降低CT扫描的辐射有效剂量（F=256.316,P<0.001）。相同扫描方案下,KARL迭代重建图像较传统FBP算法重建图像的噪声值更低,图像噪声、伪影及图像总体质量主观评分更优（P<0.05）。采用管电压100 kV,固定管电流30 mA扫描,联合KARL迭代重建胸部CT平扫的模式,能够明显降低患者所接受的辐射有效剂量,同时图像总体质量主观评分为4.0（四分位间距为0）。结论：与传统FBP重建算法相比,KARL迭代重建技术能够降低胸部CT图像噪声,提高图像质量。当管电压为100 kV,固定管电流为30 mA时,KARL迭代重建图像质量能够满足新型冠状病毒肺炎疫情期间筛查的影像学诊断要求,同时能够有效降低受检者所接受的辐射有效剂量。

Objective: To explore application of different tube voltage-tube current scanning protocol in combination with KARL iterative reconstruction in CT chestscanning for coronavirus pneumonia screening. Methods: The study prospectively enrolled 120 patients with fever subjected to CT chest scanning, who were randomly assigned to groups exa-mined with different scanning protocols: 120 kV tube voltage and automatic tube current modulation with 60 mAs effective tube current (Group A); 120 kV tube voltage and 30 mA fixed tube current (Group B); 100 kV tube voltage and automatic tube current modulation with 60 mAs effective tube current (Group C); 100 kV tube voltage and 30 mA fixed tube current (Group D). The traditional FBP algorithm reconstruction and KARL iterative reconstruction were adopted in the study. The comprehensive image quality was evaluated subjectively based on noise and artifacts. Images reconstructed with FBP algorithm and KARL iterative reconstruction were compared by Wilcoxon test and Kruskal-Wallis test. The image noise within the regions of interest was measured, and the radiation dosage of each protocol in different groups was calculated. Radiation dosage and image noisefor each group were compared with t-test and ANOVA analysis. Results: The radiation dosage of group A, B, C, D were 2.5±0.4, 1.2±0.1, 1.6±0.2 and 0.8±0.1 mSv respectively. The lower tube voltage and tube current decreased the radiation dosage significantly (F=256.316, P<0.001). Image processed with KARL iterative reconstruction had lower noise and better subjective image quality than those treated with FBP reconstruction (P<0.05). At lower radiation dosage, the image acquired with tube voltage of 100 kV and a fixed tube current of 30 mA and processed by KARL iterative reconstruction achieved a score of 4.0 for overall subjective image quality. Conclusion: Compared with FBP reconstruction, KARL iterative reconstruction might reduce noise and improve image quality. With lower radiation dosage, the CT chest scanning protocol with a tube voltage of 100 kV and a fixed tube current of 30 mA in combination of KARL iterative reconstruction is optimum choice for novel coronavirus pneumonia screening.