Feasibility of Reducing Coronary CT Angiography Dosage:The Body Mass Index Dependent mA and kV Selection Combined

Objective To evaluate the feasibility of reducing radiation dose of coronary CT angiography(CCTA) and improving the image noise uniformity through the body mass index(BMI) adapted mA and kV selection combined with prospective electrocardiographic(ECG)-gating technology.Materials and Methods 120 patients underwent CCTA were divided into control group(group A) and experimental group(group B).The retrospective ECG-gating protocol with fixed mA and kV was applied to the patients of group A.The prospective ECG-gating protocol with the BMI-adapted mA and kV was applied to group B.All of the patient's height,weight,BMI,electric current(mA),voltage(kV),noise value,CT dosage index(CTDI),effective dose(ED) were recorded.Four point scoring method was used for evaluating the image quality.Statistical processing was performed by the SPSS13.0 software.Results Correlation analysis was performed between image noise and the body weight,the height,the BMI respectively in group A.The result displayed that the image noise and BMI had significant correlation with the correlation coefficient of 0.557.The mean value of image noise in group A was smaller than that in group B,but Image noise uniformity in group B was better than that in group A.The ED of group A and group B was(21.27±1.53)mSv and(6.04±1.45)mSv.There was significant difference(P0.05) of radiation dosage between two groups,but there was no difference of image quality.Conclusion When the heart rate was lower than 70bpm and the heart rhythm was stable,the BMI-adapted mA and kV combined with prospective ECG-gating technique could reduce ED by 71.6% meanwhile the image noise uniformity be improved.