Obesity is one of those factors, said Dr. Andrew J. Einstein, an assistant professor of clinical medicine in radiology at Columbia University, who wrote an editorial accompanying the JAMA report.
Still, Einstein said, "some sites are more concerned and more careful about radiation exposure, and attention must be paid to reducing the radiation dose."
But one factor that makes the exposure report less ominous is its timing, he said. The study ended in 2007, just as a lower-radiation technique called sequential scanning was being introduced. Sequential scanning can reduce radiation exposure by 78 percent and is being widely adopted, Einstein said.
CT scanning "is a technology that is still finding its place in the constellation of diagnostic methods," he said. "It seems that it is especially good at excluding coronary disease. We can visualize the coronary arteries without doing an invasive procedure."
CT scans can be very useful in assessing the condition of someone who shows up in an emergency room complaining of vague chest pains, Einstein said. "The emergency room doctor dose not feel certain about sending such patients home without a test," he said. Yet doctors are reluctant to do an invasive test, such as angiography, which sends a probe into the heart and has its own dangers, Einstein said.
The same is true of someone seen in a doctor's office with "chest pain of an etiology which remains unclear," Gerber said. "CT angiography tends to be very valuable for patients who have symptoms or are at high risk for coronary artery disease."
It is not valuable for people who are not at high risk and have no symptoms, Einstein said. "We don't think it should be used for screening purposes," he said.
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