TUESDAY, March 17, 2020 (HealthDay News) -- There's been a large decrease in Americans' exposure to medical radiation, according to a new study.

Between 2006 and 2016, medical radiation exposure among U.S. patients fell by 20%, reversing a steep, quarter century-long rise.

The number of diagnostic and interventional radiology exams remained largely unchanged, even though the U.S. population jumped about 23 million.

The study was published March 17 in the journal Radiology.

"The radiation dose to the U.S. population went up dramatically (between 1980 and 2006) because of medical exposure, mostly from CT scanning and nuclear medicine, and that woke everybody up to the problem," said senior author Dr. Fred Mettler Jr., a radiologist at the University of New Mexico in Albuquerque.

In response to a 2008 report showing a six-fold increase in medical radiation exposure between 1980 and 2006, medical groups took steps to increase awareness of exposure. Equipment manufacturers also developed more refined technology to control doses.

But the effects of these and other efforts had been largely unknown.

"The overall trend stabilized, and the total dose to the U.S. population dropped a bit," Mettler said in a news release.

A major factor in reduced exposure was a significant decrease in the number of nuclear medicine procedures, from 17 million in 2006 to 13.5 million in 2016.

After a cut in Medicare reimbursement, many heart specialists switched from nuclear medicine-based procedures to stress echocardiography, which uses ultrasound instead of ionizing radiation.

CT scans, a major source of medical radiation exposure, increased from 67 million to 84 million scans over the 10-year study period, but average individual dose fell 6%, according to co-author Mahadevappa Mahesh, professor of radiology at Johns Hopkins University School of Medicine in Baltimore.

"One important factor is the dose modulation techniques available on most CT scanners in the country," he said in the news release. "The second factor is that overall CT detectors are becoming very efficient in the sense that they can utilize less radiation to create the same quality images."

More information

The U.S. National Library of Medicine has more on diagnostic imaging.