Paper warns of CT scan radiation dangers

The increased use of computed tomography (CT) scans, while revolutionizing diagnostic radiology, also has brought with it a greater risk of radiation and potential cancer cases, according to a recent article in the New England Journal of Medicine.1

"As compared with plain-film radiography, CT involves much higher doses of radiation, resulting in a marked increase in radiation exposure in the population," the authors said. As an example they note that a conventional anterior-posterior abdominal X-ray examination results in a dose to the stomach of about 0.25 mGy, or "grays." (One gray equals 1 joule of radiation energy absorbed per kilogram.) That dose, they asserted, "is at least 50 times smaller than the corresponding stomach dose from an abdominal CT scan."

As EDs turn with greater frequency to new technology in CT scans to speed and increase the accuracy of their examination, are they also putting their patients at greater risk? "I really don't really know what to make of all that," says Judd E. Hollander, MD, one of the researchers and a professor of emergency medicine at the University of Pennsylvania School of Medicine in Philadelphia and an ED physician at the Hospital of the University of Pennsylvania in Philadelphia. "Clearly they produce more radiation, but what is the risk of missing a heart attack?" Hollander asks. In other words, he says, "You are balancing the risks of missing a diagnosis vs. a slightly increased chance of cancer."

The radiation is one hazard when you undergo a CT scan, but the amount is significantly less than you would receive for a thallium stress test, says David Bello, MD, director of cardiovascular imaging at Orlando (FL) Regional Medical Center. "In 92% of chest pain cases [who receive a CT scan], the patient goes home, so you are saving a stress test," Bello says.

In addition, says Hollander, "We never do it on a patient who does not need it." The ED requests a CT scan for patients with a TIMI [thrombolysis in myocardial infarction] risk score of 0-2 — "Not a low enough risk to send home, high enough to admit, but no place to admit them," he explains.

Reference

  1. Brenner DJ, Hall EJ. Computed tomography — an increasing source of radiation exposure. N Eng J Med2007; 357:2,277-2,284.

Resource

For more information on the TIMI score and calculator, go to: www.timi.org. Under "TIMI Education Tools," click on "TIMI risk calculator."