Unnecessary medical imaging among Medicare beneficiaries is contributing significantly to greenhouse gas emissions, according to a new study from the Harvey L. Neiman Health Policy Institute.

Published in the Journal of the American College of Radiology, the analysis found that excess imaging exams are associated with as much as 129 kilotons of carbon dioxide equivalent (kT CO₂e) annually — roughly equal to the emissions generated by powering a town of 70,000 people for a year.

“Overuse of imaging is a strain on our healthcare system and radiology workforce,” said Dr. Michael Atalay, professor and director of cardiac imaging at Brown University and senior author of the study. “Estimates of excess imaging range from 4–30% of all imaging exams, which carries a heavy economic toll.”
Researchers used utilization data from the Neiman Almanac, which tracks imaging volumes for nearly 30 million Medicare Fee-for-Service enrollees. Inappropriate use rates were drawn from previous studies, including RAND Corporation data for CT and MR and Koch et al. (2018) for radiographs and ultrasound. Inefficiency rates varied widely by modality and body region, from just over 1% to nearly 79%.

When considering all imaging exams in the Medicare Part B population from 2017 to 2021, total annual emissions were estimated at:

MR: 8.1–136 kT CO₂e

CT: 25–178 kT CO₂e

Radiograph: 7.1–46 kT CO₂e

Ultrasound: 2.7–23 kT CO₂e

The broad ranges account for whether energy use was calculated strictly during scans or also included standby and equipment production phases. “We calculated the range of possible emissions in our work,” said Dr. Gregory Cavanagh, first author and resident physician at Lahey Hospital & Medical Center.

CT exams accounted for about half of the excess emissions from unnecessary imaging, with MR contributing roughly one-quarter.

“Emissions are likely to continue to increase given sustained increases in overall imaging volumes,” said Dr. Julia Schoen, clinical assistant professor at University of Michigan Health.

Dr. Elizabeth Rula, executive director of the Neiman Health Policy Institute, added that reducing unnecessary imaging “would also decrease the risk and cost to patients, cost to the healthcare system, and volumes contributing to the current radiology workforce shortage.”

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