A surge in the use of CT scans
in the last 25 years has led to millions of patients per
year being unnecessarily exposed to dangerous radiation
that increases their risk of cancer, according to a paper
published in the
New England Journal of Medicine.
"It has been estimated that about 0.4 percent of all cancers
in the United States may be attributable to the radiation
from CT studies," the authors wrote. Because cancer can
take a decade to appear, "this estimate might now be in
the range of 1.5 to 2.0 percent" when adjusted for the
current level of CT use.
A CT or CAT scan, which stands for computerized axial
tomography, is a three-dimensional body scan acquired
by means of an exceptionally high X-ray dose.
CT
scans have become popular because they provide more
detail than normal X-ray scans. But according to co-author
David Brenner, "The radiation dose from a CT scan is far
larger than from a conventional X-ray. It's 50 times to
100 times larger."
According to Brenner and co-author Eric Hall, the number
of CT scans performed in the United States each year
has climbed from 3 million in 1980 to 62 million in
2006. This has been directly responsible for a doubling
in the personal radiation dose experienced by the average
U.S. resident.
Based on prior studies, which found that up to one-third
of medical tests are unnecessary or could be replaced
with less expensive or risky tests, Brenner and Hall
estimate that 20 million adults and more than one million
children are receiving unnecessary CT scans each year.
Another recent study found that in the last 10 years,
the amount of CT radiation that pregnant women are exposed
to has doubled.
Brenner and Hall recommended that doctors try to limit
the use of CT scans by relying on alternate diagnostic
methods such as ultrasound and magnetic resonance imaging
whenever possible.
