Heart Imaging Exposes Patients to Wildly Different Radiation Doses Depending on Where They Live

Coronary artery disease is among the most common causes of death worldwide, and diagnosing it requires imaging tests that inevitably expose patients to ionizing radiation. How much radiation depends on the test used, the equipment available, the protocols in place, and the training of the staff performing the procedure. A study published in JAMA has now documented how dramatically these factors diverge across countries - and what that divergence means for patients.

Variation That Cannot Be Explained by Clinical Need

The study, led by Andrew J. Einstein, MD, PhD, of Columbia University, found marked variation in radiation dose to patients from diagnostic testing for coronary artery disease (CAD). The variation was not primarily explained by differences in patient characteristics or disease severity - it reflected differences in the systems delivering the care.

Two patterns stood out. First, patients in low- and middle-income countries consistently received higher doses than those in wealthier settings, likely reflecting older equipment and less standardized protocols. Second, patients undergoing coronary computed tomography angiography (CTA) showed particularly high variation, suggesting that this increasingly common imaging modality is being performed with substantially different technique across institutions and countries.

The consequences of excess radiation exposure accumulate over a lifetime. While the absolute risk from a single cardiac imaging study is small, patients with coronary artery disease often undergo multiple tests over years of clinical management. Systematic excess dose compounds into meaningful increases in long-term cancer risk, particularly for younger patients with long life expectancies ahead of them.

What Is Driving the Differences

The researchers identified three primary drivers of the variation: equipment age and capability, the existence and implementation of standardized protocols, and staff training. Modern cardiac CT scanners can achieve diagnostic image quality at substantially lower doses than older equipment, but the capital cost of replacement is prohibitive for many facilities in low- and middle-income settings. Even where newer equipment exists, the protocols governing how it is used - the specific technical parameters that determine dose - are not uniformly applied.

Training is the third variable. Operating dose-reduction features effectively requires specific knowledge; without it, staff may default to settings that prioritize image quality at the cost of patient exposure. The study's findings suggest this is a significant contributor to the variation observed.

Implications for Global Cardiac Care

Coronary artery disease rates are rising globally, with the most rapid increases occurring in low- and middle-income countries where health system capacity is most constrained. The combination of growing demand for cardiac imaging and the documented dose disparities creates a widening equity gap: the patients most likely to encounter older equipment and less standardized protocols are also the patients who are increasingly in need of the tests.

The study's authors describe the findings as identifying a "critical need for training, standardized protocols, and updated equipment to reduce radiation worldwide." They frame this as an opportunity rather than simply a problem: the variation in dose means there is substantial room for improvement without requiring new clinical evidence - the knowledge of how to reduce dose already exists and is being applied in some settings.

The study was published in JAMA (DOI: 10.1001/jama.2026.0703). Correspondence can be directed to Andrew J. Einstein at andrew.einstein@columbia.edu.