Radiation dose from cardiac computed tomography before and after implementation of radiation dose-reduction techniques

Context: Cardiac computed tomography angiography (CCTA) can accurately diagnose coronary artery disease, but radiation dose from this procedure is of concern. Objectives: To determine whether a collaborative radiation dose-reduction program would be associated with reduced radiation dose in patients undergoing CCTA in a statewide registry over a 1-year period and to define its effect on image quality. Design, Setting, and Patients: A prospective, controlled, nonrandomized study conducted during a control period (July-August 2007), an intervention period (September 2007-April 2008), and a follow-up period (May-June 2008) at 15 hospital imaging centers participating in the Advanced Cardiovascular Imaging Consortium in Michigan, which included small community hospitals and large academic medical centers. A total of 4995 sequential patients undergoing CCTA for suspected coronary artery disease were enrolled; 4862 patients (97.3%) had complete radiation data for analysis. Intervention: A best-practice CCTA scan model was used, which included minimized scan range, heart rate reduction, electrocardiographic-gated tube current modulation, and reduced tube voltage in suitable patients. Main Outcome Measures: Primary outcomes included dose-length product and effective radiation dose from all phases of the CCTA scan. Secondary outcomes were image quality assessed by a 4-point scale (1 indicated excellent; 2, good; 3, adequate; and 4, nondiagnostic) and frequency of diagnostic-quality scans. Results: Compared with the control period, patients' estimated median radiation dose in the follow-up period was reduced by 53.3% (dose-length product decreased from 1493 mGy x cm [interquartile range {IQR}, 855-1823 mGy x cm] to 697 mGy x cm [IQR, 407-1163 mGy x cm]; P<.001) and effective dose from 21 mSv (IQR, 12-26 mSv) to 10 mSv (IQR, 6-16 mSv) (P<.001). The greatest reduction in dose occurred at low-volume sites. There were no significant changes in median image quality assessment during the control period compared with the follow-up period (median image quality of 2 [images rated as good] vs median image quality of 2; P=.13) or frequency of diagnostic-quality scans (554/620 patients [89%] vs 769/835 patients [92%]; P=.07). Conclusion: Consistent application of currently available dose-reduction techniques was associated with a marked reduction in estimated radiation doses in a statewide CCTA registry, without impairment of image quality. Trial Registration: clinicaltrials.gov Identifier: NCT00640068