Radiation dose of cardiac CT scans
Posted by medconsumers on April 15, 2009
A CT scan of the coronary arteries is a good diagnostic tool, but it involves a large dose of radiation. To determine how much radiation is involved in cardiac CT scans (also known as computed tomography angiograms), researchers accessed data from 1,965 CT scans of the coronary arteries performed in 50 hospitals around the world. The average estimated dose was 12 mSv, which is the equivalent of 600 chest x-rays, although estimated exposures varied widely from place to place (5 mSv to 30 mSv).
The sixfold difference was caused by variations in CT scan protocols, hardware, and use of established strategies to minimize radiation exposure. One of them, called electrocardiographically controlled tube current modulation, or ECTCM, is well supported by evidence and is associated with a 25% reduction in radiation dose. Sequential scanning and low voltage scanning were mentioned as other effective options for limiting exposure. Only a minority of patients in this study, however, were scanned using either strategy.
Protecting patients from radiation is one of the basic principles of radiology, say the authors of this study, “Effective strategies to reduce radiation dose are available but some strategies are not frequently used.”
JAMA 2009;301:500– 7
For more information about radiation exposure from CT scans, click into our 2009 article, “CT scans—lots of radiation, little research.”