Global Study Finds Wide Gaps in Heart Imaging Radiation Doses

A landmark international study coordinated by the International Atomic Energy Agency (IAEA) and Columbia University has revealed significant global differences in the amount of radiation patients receive during diagnostic tests for coronary artery disease (CAD), raising concerns about patient safety and equity in cardiac care.

Published in JAMA (Journal of the American Medical Association), the study analysed data from more than 19,000 patients across 742 centres in 101 countries, making it the largest global assessment to date of radiation exposure from non-invasive cardiac imaging.

Researchers found that while many centres adhere to recommended dose levels, substantial variation exists between countries, regions and income groups — with patients in low- and middle-income countries (LMICs) often exposed to significantly higher radiation doses for the same procedures.

Why It Matters: CAD Still the Leading Killer

Coronary artery disease remains the leading cause of death worldwide. It occurs when plaque buildup narrows or blocks arteries supplying blood to the heart, potentially leading to chest pain, heart attacks, arrhythmias or heart failure.

As cardiac imaging use has expanded globally over recent decades, so too has exposure to medical radiation — making dose optimisation increasingly important.

"Radiation from medical imaging saves lives every day by enabling accurate diagnosis and treatment, but it must always be optimized," said Professor Andrew J Einstein, the study's principal investigator and Director of Nuclear Cardiology, Cardiac CT and Cardiac MRI at Columbia University's Vagelos College of Physicians and Surgeons.

Largest Global Snapshot of Cardiac Imaging Doses

Each participating centre contributed data from one of nine selected weeks in the fourth quarter of 2023, covering widely used imaging modalities including:

• Nuclear cardiology tests

• Coronary computed tomography (CT) scans

• Coronary CT angiography

The findings show:

• Median radiation doses varied widely by modality, geography and income level

• Facilities using optimized protocols and newer-generation equipment consistently delivered lower doses

• Patients in LMICs received higher median doses, particularly for coronary CT angiography

Coronary CT angiography is increasingly used worldwide due to improved technology and broader availability — but the study found that without optimized protocols, radiation exposure can be substantially higher.

Inequality in Exposure — Not Inevitable

"This study shows that where a patient lives, the resources available to a health system and how those resources are used can strongly influence how much radiation they receive — even when undergoing the same test," Einstein said.

Importantly, researchers stressed that reducing radiation does not mean compromising diagnostic quality. In many cases, lower doses are achievable using existing knowledge and technology.

"These differences are not inevitable," Einstein added. "The challenge is ensuring that best practices are applied consistently and equitably across the world."

Call for Training, Standards and Equipment Upgrades

The study highlights three key areas for action:

1. Improved professional training in dose-reduction techniques

2. Standardised imaging protocols across regions

3. Investment in modern imaging equipment capable of delivering lower radiation doses

The IAEA, which has worked for over 60 years to strengthen safe medical imaging worldwide, said the findings will help guide targeted support and policy development.

"This research provides critical evidence that can inform national policies and international action," said Diana Paez, Head of the Nuclear Medicine and Diagnostic Imaging Section at the IAEA and senior investigator of the study. "By identifying where radiation doses are highest and why, we can better target training, quality assurance programmes and technical support."

May Abdel-Wahab, Director of the IAEA Division of Human Health, emphasised that expanding access to cardiac imaging must go hand in hand with safeguarding patients.

"Access to diagnostic imaging is essential for tackling the growing global burden of heart disease. At the same time, patient safety must remain central," she said.

Next Steps: Harmonised Global Benchmarks

The authors call for:

• Development of regional and global radiation dose reference levels

• Expanded peer-to-peer knowledge sharing

• Stronger collaboration between regulators, professional societies and industry

• Long-term continuing medical education initiatives

As cardiac imaging continues to expand worldwide, the study underscores that radiation optimisation is both a medical necessity and an ethical obligation.

"Patients deserve the highest standards of safety while undergoing testing that is critical to heart health," Einstein said.