Medical Radiation Exposure Trending Down In US

The late-20th-century trend in the United States of increasing medical radiation exposure has been reversed, a new study finds.

"In contrast to the six-fold rise in medical radiation exposure that occurred from 1980 to 2006 in the United States, per capita radiation exposure to the population decreased by 20% between 2006 and 2016," researchers report in Radiology.

The study, funded by the US Centers for Disease Control and Prevention, was done by the US National Council on Radiation Protection and Measurements. Dr. Fred A. Mettler, Jr. of the University of New Mexico in Albuquerque and colleagues obtained effective-dose values for procedures from the published literature and used commercial, governmental and professional-society data to estimate frequency values.

In 2006, they estimate, there were 377 million diagnostic and interventional radiology exams—and "this value remained essentially the same for 2016 even though the US population had increased by about 24 million people," they write.

The number of CT scans rose from 67 million to 84 million, but the number of other nondental radiology procedures decreased from 17 million to 13.5 million.

Using the tissue-weighting factors from Publication 60 of the International Commission on Radiological Protection, the US annual per capita effective dose from diagnostic and interventional medical procedures was estimated to have been 2.9 mSv in 2006 and 2.3 mSv in 2016, with the collective dose falling from 885,000 to 755,000 person-sievert.

The most striking decrease was in nuclear-medicine procedures, which went from 17 million in 2006 to 13.5 million in 2016, with a 44% drop in per capita effective dose from 0.73 to 0.41 mSv.

"The range of doses that might be incurred by a patient can vary substantially from the average," the researchers point out. "One should always be careful to place any such estimates in the context of the typically much greater medical benefits of the procedure."

As for children specifically, the authors write, "A reduction in pediatric exposure has likely occurred due to implementation of size-specific protocols, iterative reconstruction, and awareness of radiation dose by both parents and physicians, although the exact magnitude of these efforts is difficult to assess."

Among the researchers' suggestions for the future: incorporate dose metrics into patients' medical records, standardize dose reporting and collection, and expand automated dose reporting and dose registries by professional societies.

Dr. Mettler did not respond to a request for comment.

In an editorial, Dr. Andrew Einstein of Columbia University Irving Medical Center and New York-Presbyterian Hospital, in New York City, points out there's still plenty of room for improvement.

The improvements reported in the new study are only "first steps in turning the tide," he writes.

Further, he warns, "sustainment of this trend is by no means assured, and in fact recently released (2019 data) suggest that the number of CT examinations performed in the United States may have begun to increase again."

"Redoubled efforts," he adds, "are warranted, as are novel approaches, such as better alignment of reimbursement schemes with radiation-related best practices."

—Reuters Staff

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