Patients are much more likely to die from a condition that required a CT scan than from radiation exposure from the scan, according to a study presented at the American Roentgen Ray Society's annual meeting.
For the study, Massachusetts General Hospital researchers analyzed the cases of 23,359 patients ages 18 to 35 who underwent abdominal or chest CT scans between 2003 and 2007 at three Boston hospitals. They focused their analysis on three factors: scanning frequency, patient outcome, and predicted cancer incidence.
Altogether, 5% to 50% of the chest CT patients and 2% to 33% of the abdominopelvic CT patients died within four years. Using BEIR-VII calculations, the researchers estimated that just 12 of all chest CT patients and 23 of the abdominopelvic CT patients would have developed cancer from scan radiation.
The study did find that mortality rates were higher in patients who received more CT scans. For example, only 5% of patients who received one or two chest CTs died over the study period, compared to 50% of patients who received more than 15 scans.
However, study author Rob Zondervan notes that patients receiving many scans are more likely to have serious conditions "where their expected mortality was likely to occur much sooner than the chances of the radiation-induced cancer taking effect."
According to Zondervan, "We're trending toward the camp that says you should err on the side of scanning rather than not, because the chance of dying from one to two scans is very small. More often than not, patients should be getting that CT scan because the risk of the underlying cause is higher than from radiation."
Nonetheless, he notes that patients should avoid scan radiation when possible. "Ask whether the same information can be obtained in [another] way," he says, adding, "In some cases, ultrasound might be better for, say, investigating possible appendicitis" (Dotinga, HealthDay, 5/1; Bankhead, MedPage Today, 5/2).