基于不同管电压的人工智能重建算法对胸部体模CT扫描图像质量和辐射剂量的影响研究

Study on the effects of AI reconstruction algorithm based on different tube voltages on CT imaging quality and radiation dose of chest phantom

目的:基于成年男性仿真胸部体模(PH-N1)CT扫描,探究不同管电压结合人工智能(AI)重建(CI)算法对胸部体模CT扫描图像质量和辐射剂量的影响。方法:采用512层超高端CT分为4种管电压对体模进行扫描,分别为70 kV、80 kV、100 kV和120 kV,对不同管电压的CT扫描图像采用10%、30%、50%、70%和90%CI算法重建1 mm薄层图像,比较4组扫描的容积剂量指数(CTDIvol)和剂量-长度乘积(DLP)。测量图像主动脉、腹壁脂肪及竖棘肌的CT值、标准偏差(SD)值,由两名5年以上工作经验的高年资诊断医师独立双盲的对图像质量进行5分制评估,并行Kappa一致性检验。采用单因素方差分析比较图像目标组织的CT值、SD值差异。采用Friedman秩和检验比较组间主观图像质量的差异。结果:4种不同管电压的CTDIvol和DLP比较,差异有统计学意义(F=1855.617、3996.118,P<0.05)。在70 kV管电压下,10%、30%、50%、70%和90%CI算法重建的主动脉、腹壁脂肪及竖棘肌的CT值比较,差异均无统计学意义(P>0.05),而SD值差异均有统计学意义(F=32.267、53.327、14.873,P<0.05)。在90%权重的CI算法重建4种不同管电压下,主动脉、腹壁脂肪及竖棘肌的CT值随着管电压的降低,CT值逐渐降低,差异有统计学意义(F=139.899、2563.93、219.231,P<0.05)。两名诊断医师对各组图像的主观评分一致性较好(Kappa=0.712~0.869)。结论:CI算法在70 kV管电压下90%权重的CI算法重建图像与80 kV、90 kV、120 kV图像相比,可以明显降低辐射剂量,同时图像具有良好信噪比。

Objective:To investigate the effects of different tube voltages combined with artificial intelligence reconstruction algorithm(CI)on the computed tomography(CT)imaging quality and radiation dose of chest phantom on the basis of the CT scan for an adult male simulated chest phantom(PH-N1).Methods:A 512-slice CT scanner of ultrahigh-end was adopted to conduct scan,and the images were divided into 70 kV group,80 kV group,100 kV group and 120 kV group according to different tube voltage.For 4 groups of CT scan images with different tube voltages,the 10%,30%,50%,70%and 90%CI were adopted to reconstruct 1mm thin layer image.The CT volume dose index(CTDIvol)and the dose-length product(DLP)of the scans of 4 groups were compared.The CT values and standard deviation(SD)values of the aorta,abdominal wall fat and erector spine muscle were measured.Two senior diagnostic physicians with more than 5 years of work experience independently and double-blindly evaluated the image quality by using 5-point scale.A Kappa consistency test was conducted.One-way analysis of variance was adopted to compare the differences of CT values and SD values of the tissues of image targets.The Friedman rank-sum test was adopted to compare the differences of subjective image qualities among different groups.Results:The differences of CTDIvol and DLP among 4 groups with different tube voltages were significant(F=1855.617,3996.118,P<0.05),respectively.Under 70 kV tube voltage,there were no significant differences in CT values of the aorta,abdominal wall fat and erector spine muscle,which were reconstructed by using 10%,30%,50%,70%and 90%CI(P>0.05),while the differences of SD values among them were statistically significant(F=32.267,53.327,14.873,P<0.05),respectively.Under the different tube voltages of 4 groups,which were reconstructed by 90%CI,the CT values of aorta,abdominal wall fat and erector spine muscle gradually decreased with decreasing of tube voltage,the differences were significant(F=139.899,2563.93,219.231,P<0.05),respectively.The consistency of subjective scores between two diagnostic physicians was better for each group of images(Kappa=0.712~0.869).Conclusion:Compared with 80 kV,90 kV and 120 kV images,the reconstructed images with 90%CI algorithm under 70 kV tube voltage can significantly reduce the radiation dose,and the images have a favorable signal-to-noise ratio at the same time.