CT Scans Increase Cancer Risk Estimates in Multiple-Imaged Emergency Department Patients

Physicians should review a patient's computed tomography (CT) imaging history and cumulative radiation dose when considering whether to perform another CT exam.

Researchers from Brigham and Women's Hospital (Boston, MA, USA) and Washington University School of Medicine (St. Louis, MO; USA) reported that their study included 130 patients who had at least three emergency department visits within one year in which they had a CT scan of the neck, chest, abdomen, or pelvis. "We gathered the recent CT exam histories for each of these patients and found that half had undergone 10 or more CT scans in the previous eight years, up to a maximum of 70 CT scans," said Aaron Sodickson, M.D., Ph.D. "Using typical dose values and standard risk estimation methods, we calculated that half of our group had accrued additional radiation-induced cancer risks above baseline greater than 1 in 110, up to a maximum of 1 in 17."

According to Dr. Sodickson, a patient's cumulative risk of radiation-induced tumors is believed to increase with increasing cumulative radiation dose. The degree of risk is additionally increased for patients scanned at young ages and is typically greater for women than for men. There is no absolute threshold, however, he reported, and the potential risks of radiation-induced cancer must be weighed against the expected clinical benefits of the CT scan for the patient's specific situation.

"CT is a tremendously valuable clinical tool in a wide variety of settings and disease processes, and as a result CT utilization has grown rapidly in recent years. Continued attention will be needed to keep radiation risks in check through a combination of technological advances, optimized imaging techniques, appropriateness criteria and patient-specific risk/benefit assessments," concluded Dr. Sodickson.

This study appears in the April 2009 issue of the American Journal of Roentgenology (AJR).

Related Links:
Brigham and Women's Hospital
Washington University School of Medicine