Are CT Scans Sometimes Too Risky?
Study Shows Radiation Doses From CT Scans Vary Widely
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Radiation From CT Scans continued...
The dose ranges were high. For example, for a head CT scan, while the median dose was 2, the range was 0.3 to 6. "'That is a huge range," she says.
Most dramatic, she says, was the dose and the dose range for a multiphase abdomen and pelvic series. While the median dose was 31, the range was from 6 to 90.
Then the researchers estimated the lifetime cancer risk linked to the CT scan. They estimated that one in 270 women and one in 600 men who got a CT coronary angiogram at age 40 would develop cancer from that scan. They also estimated that one in 8,100 women and one in 11,080 men who had a routine head CT scan at age 40 would develop cancer.
CT Scans and Cancer
In another report published in the Archives of Internal Medicine, a team of researchers led by Amy Berrington de Gonzalez, DPhil, an investigator at the National Cancer Institute, also estimated the risk of cancer attributable to CT scans.
After looking at data from previous reports of radiation-linked cancer risk, insurance claims and nationwide surveys, they concluded that 29,000 future cancers could be related to the 70 million CT scans performed in the U.S. in 2007.
This includes an estimated 14,000 cases resulting from scans of the abdomen and pelvis; 4,100 from chest scans; 4,000 from head scans; and 2,700 from CT angiograms. One-third of these projected cancer cases would occur following scans performed on people ages 35 to 54. Two-thirds of the cancers would be in women, according to a news release.
The high number of cancers attributed to scans of the abdomen and pelvis is not surprising, according to Berrington de Gonzalez, since they are so commonly done. "One-third of the 70 million [scans] were abdominal and pelvic."
The new research will hopefully raise awareness among doctors and consumers, says Rita Redberg, MD, professor of medicine at the University of California San Francisco and editor of the Archives of Internal Medicine, who wrote an editorial to accompany the reports.