Several recent studies have suggested that patients have been unnecessarily exposed to radiation from CTs or have received excessive amounts, but two new studies published Tuesday in the Archives of Internal Medicine are the first to quantify the extent of exposure and the related risks. Each year that current scanners are used, researchers reported, 14,500 deaths could result. In one study, researchers from UC San Francisco found that the same imaging procedure performed at different institutions -- or even on different machines at the same hospital -- can yield a 13-fold difference in radiation dose, potentially exposing some patients to inordinately high risk. While a normal CT scan of the chest is the equivalent of about 100 chest X-rays, the team found that some scanners were giving the equivalent of 440 conventional X-rays. The absolute risk may be small for any single patient, but the sheer number of CT scans -- more than 70 million per year, 23 times the number in 1980 -- will produce a sharp increase in cancers and deaths, experts said. "The articles in this issue make clear that there is far more radiation from medical CT scans than has been recognized previously," Dr. Rita F. Redberg of UC San Francisco, editor of the journal, wrote in an editorial accompanying the reports. Even many otherwise healthy patients are being subjected to the radiation, she said, because emergency rooms are often sending patients to the CT scanner before they see a doctor. Whole body scans of healthy patients looking for hidden tumors or other illnesses are also becoming more common, even though they rarely find anything wrong. The irony is that, by exposing healthy people to radiation, the scans may be creating more problems than they solve. CT scans, short for computed tomography, provide exceptionally clear views of internal organs by combining data from multiple X-ray images. But the price for that clarity is increased exposure to X-rays, which cause mutations in DNA that can lead to cancer. When the screening is used for diagnostic purposes, the benefits outweigh the risks, most experts agree, though the toll increasingly can't be ignored. SOURCE:LATIMES.COM



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