Algorithm for radiation dose reduction with helical dual source coronary computed tomography angiography in clinical practice

Background: Strategies to reduce the radiation dose of coronary computed tomography angiography (CCTA), while maintaining diagnostic image quality, are imperative for cardiac CT. Objective: We aimed to reduce radiation dose during helical dual-source CCTA by combining lower tube voltage, shortest possible full tube current (FTC) window, and minimal tube current outside the FTC window, and to develop a patient-based algorithm for applying these dose-reduction components. Methods: We compared FTC at 70% of the cardiac cycle (FTC70) to a 45% to 75% window (FTC45-75) using both 100 and 120 kVp (N=118). FTC70 was used in patients with heart rates <70 beats/min, no arrhythmia, age <65 years; 100 kVp was used in patients with body mass index (BMI) <30, a low coronary calcium score (CCS), and no stents. Objective and subjective image quality were assessed. Results: Compared with FTC45-75 at 120 kVp, radiation dose was reduced by 66% for FTC70 at 100 kVp (mean radiation dose: 4.4 ± 0.9 mSv) and by 43% for FTC70 at 120 kVp. 99% of 780 segments in the FTC70 group were of diagnostic quality. Noise, signal-to-noise ratio, and contrast-to-noise ratio were comparable between FTC70 and FTC45-75 for both 100 and 120 kVp. BMI, CCS and maximal heart rate variation were predictors of image quality. Tube voltage, FTC window width, scan length, and average heart rate were predictors of radiation dose. Conclusions: A successful patient-based algorithm for radiation dose reduction during helical CCTA using DSCT has been developed and validated in clinical practice.