CT Scan Scare

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Computed tomography (CT) helps doctors diagnose problems by recording high-resolution “slices” of a patient’s internal organs. CT is faster and quieter than magnetic resonance imaging (MRI) and provides sharper images than ultrasound. But does CT increase cancer risk? A study published in the December 14, 2009, issue of Archives of Internal Medicine suggests that the radiation emitted by CT scans conducted in one year — 2007 — could cause 29,000 malignant growths in U.S. patients.

The study may be causing unnecessary alarm, says William Davros, PhD, Head of the Medical Physics Section in the Imaging Institute at Cleveland Clinic. The low exposure levels cited in the study make it hard to determine whether there’s a direct link between CT scans and cancer.

Considering the amount of information that physicians get for the small radiation dose per scan, says Dr. Davros, “CT is actually a good deal. It saves many lives by picking up cancers early and allowing for therapies.” Cleveland Clinic has guidelines for ensuring that CT scanners use the lowest appropriate exposure settings, and radiologists track all patients’ exposures. Patients whose conditions require multiple scans might be able to alternate CT scans with MRI and ultrasound to further reduce exposure.

Dr. Davros encourages patients who still have concerns to ask their physician if a CT scan that shows a problem would change the course of their treatment. If not, then ultrasound or MRI might be alternatives.