Are CT Scans Sometimes Too Risky?
Study Shows Radiation Doses From CT Scans Vary Widely
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
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.
''I don't think people routinely question, 'Do I need this CT scan at this
time?'" she tells WebMD.
And they should, she says. If a doctor orders a CT scan, she advises: "Ask
your doctor, 'How is this CT scan going to contribute to my medical care?'
[and] 'How will it change how you are going to treat me and how will that
The new findings about radiation doses and ranges should be balanced with
consideration of the benefits of the technique, says Donald Frush, MD, chairman
of the American College of Radiology Commission on Pediatrics and professor of
radiology and pediatrics at Duke Medical Center, Durham, N.C. ''CT is a very
helpful technique," he says. "It's one of the greatest medical advances."
But he, too, says consumers should specifically ask if the CT scan is
necessary or if another imaging technique that doesn't require radiation, such
as ultrasound, could be used.
Part of the problem, Smith-Bindman says, is a lack of consensus on what the
radiation dose should be for different CT scans. In some cases, radiologists
set the parameters, she says; other times manufacturers do. It's done in a
variety of ways, she says.
The FDA has done survey studies, says Smith-Bindman, finding that ''doses
need to be between X and Y." More oversight from the FDA would help, she