When we’re in the dark, it’s a natural instinct to turn on the lights and try to see. The hospital is no exception. Whether it’s to confirm a diagnosis or to achieve clarity about what condition might be causing a symptom, ordering imaging—MRIs, CT scans, and others—is a ubiquitous part of standard medical practice. 

While many scans and images offer critical insight, some are considered low value, according to criteria established by the American College of Radiology. 

There’s an unseen cost to these unnecessary medical scans, say Michael Atalay, MD, PhD, P’27, director of cardiac imaging at Brown, and Gregory Cavanagh MD’24, who quantified the waste accrued by excess imaging. 

Their findings, published in the Journal of the American College of Radiology, were staggering. Using data from various sources, along with the US Environmental Protection Agency’s emissions calculator, the research team found that, during the four-year study period, inappropriate imaging may have generated up to about 129 kilotons of greenhouse gases annually—equivalent to a year of emissions from a 70,000-person town. 

“Insurance companies are paying for all of these [unnecessary] studies. The radiologist is paying for it with a huge burden of unnecessary studies to read. Patients are exposed to ionizing radiation, potentially productivity loss”—taking time away from work for imaging appointments—“the inconvenience of followup, and unnecessary anxiety,” says Atalay, a professor of radiology and of medicine. “But we’re all paying for it in terms of unnecessary carbon emissions.” 

Atalay’s longstanding interest in climate and the biosphere sparked this project, says Cavanagh, a diagnostic radiology resident at Lahey Hospital & Medical Center in Burlington, MA. When chatting with Atalay during his third-year radiology rotation, Cavanagh saw the potential to give a “1,000-foot perspective of where radiology can come into contact with the environment.” 

Cavanagh, who as a medical student served on The Warren Alpert Medical School’s Environmental Coalition, says he sought to convey through the paper that small actions can have an enormous ripple effect. 

“The sheer number of imaging studies is so large across the country and the world that any marginal amount of waste amplified over the millions of studies can end up accounting for a tremendous amount of energy wasted,” Cavanagh says. While their study focused on electrical energy waste, he points out that material waste accrues too, in the form of excess contrast agents and packaging, equipment needed to process the imaging, and cleaning materials after studies are finished. 

Atalay believes education can make a difference even before f irm policies are put in place to reduce unnecessary imaging. “One potential strategy for reducing low-value imaging is to offer nudges during the ordering process that help guide care providers to make appropriate imaging choices,” he says. 

“Care providers order studies because they have the patient’s best interests at heart,” Atalay adds. “Physicians and other care providers often feel an onus to be near-perfect. Being wrong is not an option; this means that we find ourselves chasing zebras, with more and more testing, even though the hoofbeats we’re hearing are from horses.” 

“Ultimately, we don’t want to sacrifice patient care,” Cavanagh says. “That’s why we sometimes need to do a systems-wide analysis in health care. Even though I want to save people today, I don’t want to hurt people tomorrow.”