New analysis shows that avoidable imaging studies could generate as much CO₂ as powering a town of over 70,000 people for a year.
A new study from the Harvey L. Neiman Health Policy Institute found that unnecessary imaging studies in Original Medicare are associated with up to 129 kT of CO2 emissions—the same as would be produced from powering a town of over 70,000 people for a year.
The research, published in the Journal of the American College of Radiology, demonstrates the opportunity for the field of radiology to meaningfully reduce its environmental footprint.
“Overuse of imaging is a strain on our healthcare system and radiology workforce. Estimates of excess imaging range from 4-30% of all imaging exams, which carries a heavy economic toll. The goal of our study was to determine the extent to which unnecessary imaging is contributing to global warming via greenhouse gas emissions,” says senior author Michael Atalay, MD, PhD, professor and director of cardiac imaging at Brown University, in a release.
Breaking Down Imaging Emissions
To explore this question, the researchers obtained the yearly total number of imaging studies using The Neiman Almanac, an online data tool that publishes annual imaging utilization for 100 percent of the nearly 30 million Medicare Fee-For-Service Beneficiaries. Excess imaging was calculated using estimates published by the RAND Corporation on inappropriate use of CT and MR imaging, the highest emission modalities, and from Koch et al (2018) for radiograph and ultrasound studies. Imaging inefficiency rate varied by modality and body region from 1.1% to 78.9%.
The study reported that total average yearly greenhouse gas emissions from all imaging exams in the Medicare Part B population from 2017-2021—not just excess exams—were estimated to be 8.1-136 kT CO2e for MRI, 25-178 kT CO2e for CT, 7.1-46 kT CO2e for radiographs, and 2.7-23 kT CO2e for ultrasound.
“We calculated the range of possible emissions in our work. The low-end estimates only included energy used during an exam, whereas the high-end estimates also included the energy required when the scanners are in stand-by mode or in production phase between scans,” says first author Gregory Cavanagh, MD, resident physician at Lahey Hospital & Medical Center, in a release.
Impact of Unneeded Imaging
The total yearly estimated greenhouse gas emissions from all inappropriate imaging exams from 2017-2021, across all modalities, was 3.55-129.2 kT/year. Unnecessary CT exams contributed approximately half of these excess emissions, and another quarter resulted from MR.
“Emissions are likely to continue to increase given sustained increases in overall imaging volumes over the past decade, and the potential for further increases related to climate-change related exposures and events,” says Julia Schoen, MD, MS, clinical assistant professor, University of Michigan Health, Ann Arbor, Mich, in a release.
Elizabeth Rula, PhD, executive director of the Neiman Health Policy Institute, adds in a release, “Our analysis demonstrates the potential to meaningfully reduce our carbon footprint by decreasing unnecessary imaging orders. These findings add an additional, important reason to reduce inappropriate imaging utilization, which 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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