Medical imaging procedures are an important source of radiation exposure that should be studied further to prevent potentially dangerous levels over a lifetime, a new study says, echoing concerns raised by Boston doctors in this Globe story.
Radiation has been linked to cancer, but there is little scientific evidence on the long-term cumulative effects of radiation exposure in people having tests or procedures using radiation, including CT scans and heart procedures guided by radioactive substances.
The new study, appearing in tomorrow's New England Journal of Medicine, examined three years of insurance claims data for almost a million adults under 65 in five locations around the country. The researchers, led by Dr. Reza Fazel of Emory University School of Medicine, excluded radiation treatments for cancer in their analysis.
CT scans and nuclear imaging made up nearly three-quarters of the radiation received, the study says. Most imaging took place outside the hospital.
The researchers found that most participants did not have worrisome levels of radiation exposure, but 20 percent of them did receive at least moderate levels of radiation over the three-year study period. Generalized to the US population, 4 million Americans would have annual radiation exposure equal to the annual limit set for people who work in health care or the nuclear industry, the authors write.
"Our findings indicate that the current pattern of use of medical imaging in the United States among non-elderly patients is exposing many to substantial doses of ionizing radiation," they write. "Strategies for optimizing and ensuring appropriate use of these procedures in the general population should be developed."
In an editorial accompanying the Journal article, Dr. Michael Lauer of the National Heart, Lung, and Blood Institute calls for large-scale randomized trials to determine which imaging tests and procedures yield benefits worth their risks.
"Though the danger may be small, it is cumulative and hence of particular relevance to the small but substantial minority of people who ... undergo clusters of tests," he writes. "Exposure to even moderate degrees of medical radiation presents an important yet potentially avoidable public health threat."
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