Patients exposed to significantly more radiation during cardiac imaging exams in some regions
New research is sounding the alarm on the amount of radiation patients undergoing cardiac imaging are exposed to, prompting experts to call for updated protocols.
Coronary artery disease (CAD) is the leading cause of death worldwide, but mortality rates have been falling for years in some parts of the world. This is thanks, in large part, to early detection methods, such as noninvasive imaging; SPECT and PET nuclear cardiac imaging, cardiac CT for coronary artery calcium scoring and coronary computed tomography angiography (CCTA) have each played a significant role in improving the diagnosis and treatment of CAD. However, these exams come with the caveat of patient radiation exposure.
A new paper in JAMA details how these exposure levels during cardiac imaging vary across the world, revealing that median doses in certain regions far exceed standard recommendations.
“...Limited attention has been paid to ensuring implementation of safety standards for imaging modalities that expose patients to ionizing radiation, such as nuclear imaging and coronary computed tomography angiography, as these technologies have disseminated worldwide,” Andrew J. Einstein, MD, PhD, with the Division of Cardiology at Columbia University Irving Medical Center/NewYork-Presbyterian Hospital, and colleagues noted. “As CAD incidence and mortality increase in many places across the world, there is a growing need for higher use of diagnostic imaging to facilitate early detection and treatment of at-risk patients, notwithstanding the potential for significant numbers of radiation-attributable cancers from this testing.”
Using data from the International Atomic Energy Agency, researchers compared radiation dose levels from more than 19,000 adults undergoing noninvasive CAD imaging at 742 centers in 101 countries during a single week. Exposure metrics for each exam were analyzed alongside regional data to determine whether certain factors, such as median income level for the area, were associated with higher radiation doses.
This revealed widespread variations in effective doses throughout the world and, as expeced, varying levels of exposure based on exam type. The median effective dose was lowest for coronary artery calcium scoring, at 1.2 mSv; PET exams were next in line, at 2.0 mSv, followed by SPECT, at 6.5 mSv and CCTA, at 7.4 mSv. Nuclear cardiology exams were more prevalent, with centers conducting 25% more SPECT and PET exams in comparison to CCTAs; patients who completed nuclear exams had a median dose of equal to or less than 9 mSv, as is recommended in guidelines.
Doses for the same procedures varied widely across regions. For example, exams in Western Europe yielded the lowest median doses for nuclear exams (4.8 mSv) and CCTA (4.6 mSv). These figures were significantly higher in Latin America and Africa. Researchers pinned this finding on an inverse relationship between country income level and median dose levels. These levels were 20% higher in low- and middle-income countries compared to high-income countries for nuclear cardiology, and up to 96% higher in low- and lower-middle–income countries compared to high-income countries for CCTA.
The variations could be attributed to multiple factors, including the technology used (type of scanner, age of equipment, etc.), individual equipment features, varying scan protocols and differing best-practices guidelines. The group believes their findings can be used to help reduce radiation doses globally. This is especially important given the rising use of imaging for coronary artery disease.
“These findings have far-reaching implications,” the authors noted. “The data can inform national and regional policies aimed at standardizing imaging practices, particularly in [low- and middle-income countries] where doses are typically higher and regulatory frameworks may be less robust.”
Read more from the study here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.