One-third of patients unaware of rad exposure with CT, cardiac SPECT

Patient knowledge and understanding of radiation from diagnostic imaging is lacking, according to a research letter published online Dec. 31, 2012, in JAMA Internal Medicine. More than half of patients surveyed heard nothing in the media about radiation from medical imaging, and many of those aware of radiation exposure substantially underestimated dose.

Janet M. Busey, MS, from University of Washington School of Medicine in Seattle, and colleagues conducted a prospective survey study to document patient knowledge and understanding of radiation from CT and SPECT scans.

The researchers enrolled 235 patients undergoing nonurgent outpatient CT and cardiac SPECT scans from February 2011 through December 2011.

A total of 69 percent of patients referred to their healthcare provider as their primary source of health information. Sixty-six percent of patients believed their scans were definitely necessary. Three percent reported thinking about radiation prior to the scan.

Among patients who understood that the scan exposed their body to radiation, 88 percent were not worried about radiation, and 85 percent underestimated the amount of radiation exposure. “Most patients (95 percent) reported that it was more important to figure out what might be wrong than to worry about scan radiation,” wrote Busey et al.

The researchers noted several possible reasons for patients’ lack of knowledge, including providers’ limited knowledge of radiation and the difficulty of explaining and understanding radiation exposure.

“These data suggest that patients undergoing nonurgent CT and cardiac SPECT wish to be informed of imaging risks but have limited knowledge and understanding of radiation dose and associated health risks. …These data suggest that many patients have a limited ability to make well-informed decisions about imaging that involves radiation,” concluded Busey and colleagues.