Effect of iterative reconstruction algorithm combined with CARE dose 4D on reducing radiation dose in liver CT

doi:10.3969/j.issn.1002-7386.2015.07.002

Abstract：Objective To investigate the influence of iterative reconstruction algorithm ( IRIS) combined with CARE dose 4D on reducing radiation dose and improving image quality in liver CT .Methods (1) Human cadaver study :human cadaver was scanned for twelve times by emotion 16-slice CT scanner with same tube voltage 130 kV and different tube currents from 30mAs to 250mAs with increment of 20mAs.The images were reconstructed with IRIS and FBP respectively ,and the data were analyzed before clinical study .(2)Clinical study:120 patients were randomly divided into two groups ,group A and group B,with 60 patients in each group.The patients in group A received liver CT (130kV,CARE dose 4D and reference mAs of 150),and images were reconstructed with IRIS and FBP ,redpectively.The patients in group B were scanned by CT (130kV, reference mAs of 250),and images were reconstructed with IRIS and FBP respectively .CT dose index volumes (CTDIvol), dose length product ( DLP) were recorded .The image quality was evaluated by three radiologists blindly with objective methods (noise measurement and CNR calculating etc ) as well as subjective methods.Results CTDIvol and DLP were 2.35 ~16.3mGy and 63.4~287.5mGycm,respectively,in group A,however,which were 25.7mGy and 523.8~586.6mGycm in group B,respectively,which in group A were decreased by 50%~70%.Image quality in both group A1,group B1,group B2 met diagnostic requirements .The image quality in group B1 was better than that of group B2,however,there was no significant difference in image quality between group A1 and group B2 ( P >0.05).The image quality in group A2 was the worst,which could not meet diagnostic requirements .Conclusion IRIS combined CARE dose 4D can improve the image quality under the condition of the same dose , which can reduce the radiation dose of liver CT under the condition of guaranteeing the image quality,so it is worthy of clinical spreading application .