Application of iterative reconstruction technique(iDose~4) on dose reduction at body mass index-based CT coronary angiography

Objective To explore the effect of iterative reconstruction technique(iDose4)on dose reduction at body mass index(BMI)-based CT coronary angiography(CTCA)with prospective gating.Methods A total of 120patients who underwent CTCA with prospective gating were divided into 4groups according to BMI,i.e.group A(BMI≤21kg/m2),group B(21kg/m2BMI≤24kg/m2),group C(24kg/m2BMI28kg/m2)and group D(BMI≥28kg/m2),each group had 30patients.The tube current was set as 100mAs,150mAs,200mAs,and 250mAs for group A to group D,respectively.Three series of images were reconstructed with filtered back projection(FBP),iDose4-3and iDose4-5for each subject.Two radiologists assessed subjective image quality using 4-point scale.Objective image noise was measured.CT dose index volumes(CTDIvol)and dose length product(DLP)were recorded,while effective dose(ED)was estimated.Results In each group,significant differences among three reconstruction methods were found respect to objective image noise(all P0.001).Compared with FBP,the objective image noise reduction was 23.11%and 35.61%for iDose4-3and iDose4-5,respectively.The ratio of the subjective image score≥3of iDose4-3and iDose4-5images in each group was higher than that of FBP images(P0.05),while no statistical difference was found between iDose4-3and iDose4-5.The average ED of group A to group D was(1.36±0.10)mSV,(1.98±0.10)mSV,(2.67±0.21)mSV and(3.33±0.24)mSV,respectively.Conclusion BMI-based iterative reconstruction technique(iDose4)and prospective gating can effectively reduce radiation dose of CTCA.