Fewer than 30 percent of emergency department (ED) providers have accurate knowledge of lifetime cancer risk attributable to commonly performed CT scans, according to the results of a questionnaire published in the December issue of the American Journal of Roentgenology.

The study also revealed that physicians have significantly better knowledge about CT radiation risks than do midlevel providers, such as physician assistants and nurses, according to Savita Puri, MBBS, MPH, of the University of Rochester, New York, and colleagues.

The work was spurred by the fact that per capita medical radiation dose increased from 0.67 mSv/year in 1980 to more than 3 mSv/year in 2005. In 2007, approximately 70 million CT scans were performed in the U.S. and 29,000 future cancers can be predicted to occur as a result. Individual risks are small and generally outweighed by the benefits of a scan, but because radiation dose risks are real, curbing unnecessary scans is important. “It is now generally accepted that approximately 30 percent of all CT scans could be avoided altogether or replaced by a different diagnostic tool, but the current utilization trends are headed in the opposite direction,” wrote the authors.

To assess providers’ knowledge of lifetime dose risks, 67 physicians and midlevel providers at the University of Rochester Medical Center completed a multiple-choice questionnaire involving items about CT cancer risks and the provider’s strategy for risk-benefit analysis.

In addition to finding that less than one-third of respondents had adequate knowledge of lifetime cancer risk attributable to medical radiation, the authors found that 17 percent underestimated the risk while 42 percent overestimated the risk.

Providers with greater clinical experience were more likely to conduct a risk-benefit analysis, consider patients’ radiation dose history and avoid unnecessary CT scans. “These findings suggest that providers with greater clinical experience, although lacking accurate knowledge of the lifetime cancer risk attributable to radiation, through cumulative clinical acumen have developed skills that enable them to effectively conduct a risk-benefit analysis, effectively communicate with the patients the risks and benefits before ordering a CT scan, and thus minimize unnecessary use of CT scans,” wrote Puri and colleagues.

Providers with fewer years of clinical experience were more likely to have knowledge about lifetime cancer risk attributable to CT radiation, and may rely more on technology for accurate diagnostic information which “can often prove to be unnecessary once the results become available,” wrote the authors.

“It is hoped that the providers will not stop here, but will continue to build on the knowledge base and help prevent the unnecessary use of CT scans by conducting an accurate risk-benefit analysis.”