Yet despite the upward trend in the overall use of CT scans, with an apparent doubling of both low- and high-dose radiation exposure within the two time frames, the researchers determined that there was a "significantly lower risk of developing cancer from CT than previous estimates."
Cancers associated with radiation exposure were estimated to be 0.02 percent of the first group and 0.04 percent of the second.
Previous estimates ranged from 1.5 percent to 2 percent, said the authors.
While the results are good news, the consequences of CT scans should continue to be monitored, the authors concluded.
Dr. Robert Zimmerman, executive vice chair of radiology at Weill Cornell Medical Center in New York City, said that assessing CT scan risk is a tricky endeavor. He believes patient needs should be assessed on a case-by-case basis so as to limit exposure as much as possible.
"It doesn't surprise me that the secondary cancer risk is low," he said. "But it's a very complicated epidemiological notion to deal with. Does every amount of cancer radiation exposure increase your risk, or is there a level of exposure that your body can always tolerate and recover from? It's very, very hard to say," Zimmerman pointed out.
"For better or worse we are now conducting an experiment on the entire population of the U.S. as to whether or not low-dose radiation exposure is going to raise risk of developing cancer," he said.
Reducing radiation doses across the board should be the goal, regardless of the study's finding, he noted. "We always want to make sure that the dose used when scanning is as low as possible, and that scanning only takes place when necessary and beneficial to the patient," he said.
Because this study was presented at a medical meeting, the findings should be viewed as preliminary until they are published
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