Worldwide Radiation Dose in Coronary Artery Disease Diagnostic Imaging

Importance: In recent decades, there has been marked worldwide growth in diagnostic testing for coronary artery disease (CAD), with several common imaging modalities exposing patients to ionizing radiation. Objective: To examine worldwide radiation doses for patients undergoing noninvasive CAD diagnostic testing. Design, Setting, and Participants: This worldwide, cross-sectional study was conducted of radiation dose from noninvasive CAD imaging in 2023, using a consecutive sample of all 19 302 adults undergoing noninvasive CAD diagnostic testing at 742 centers in 101 countries during a single week in October to December 2023. Exposures: Participants underwent CAD testing with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) nuclear cardiac imaging, cardiac computed tomography for coronary artery calcium scoring (CACS), or coronary computed tomography angiography (CCTA). Main Outcomes and Measures: The primary outcomes were radiation effective dose to patients and the percentage of centers with median effective dose less than or equal to 9 mSv, as recommended in guidelines. Results: Of 19 302 patients, 8515 (44%) were females and the median (IQR) age was 63 (54-71) years. Effective dose varied considerably across diagnostic modalities, with median (IQR) effective dose of 1.2 (0.7-2.2) mSv for CACS, 2.0 (1.6-2.4) mSv for PET, 6.5 (3.9-8.6) mSv for SPECT, and 7.4 (3.5-15.5) mSv for CCTA. Significantly more centers performing nuclear cardiology than CCTA (81% vs 56%; P < .001) and patients undergoing nuclear cardiology studies than CCTA (79% vs 56%; P < .001) achieved median dose of less than or equal to 9 mSv. Doses for the same procedure differed significantly between world regions, being lowest in Western Europe (median [IQR], 4.8 [2.3-7.3] mSv for nuclear cardiology and 4.6 [2.4-9.8] mSv for CCTA) and highest in Latin America for nuclear cardiology (median [IQR], 7.8 [5.3-9.7] mSv) and Africa (median [IQR], 25.2 [14.7-35.3] mSv) for CCTA (P < .001 for all). In regression modeling, there was an inverse relationship between country income level and dose. Patient dose was 20% (95% CI, 3.6%-38.4%) higher in low- and middle-income countries than in high-income countries for nuclear cardiology, and as much as 96% (95% CI, 41.7%-170.8%) higher in low- and lower-middle-income countries than in high-income countries for CCTA (P < .001). Marked variation was observed within income levels and world regions. Conclusions and Relevance: Given increasing rates of CAD worldwide, these findings of marked variation in radiation dose to patients from diagnostic testing identify a critical need for training, standardized protocols, and updated equipment to reduce radiation worldwide. This especially affects patients in low- and middle-income countries and patients undergoing CCTA. There are therefore important opportunities to improve the quality of CAD diagnosis for patients across the globe.