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Source: ONE News
Radiation from CT scans done in 2007 will cause 29,000 cancers
and kill nearly 15,000 Americans, researchers said.
The findings, published in the Archives of Internal Medicine, add
to mounting evidence that Americans are overexposed to radiation
from diagnostic tests, especially from a specialized kind of X-ray
called a computed tomography, or CT, scan.
"What we learned is there is a significant amount of radiation with
these CT scans, more than what we thought, and there is a
significant number of cancers," said Dr Rita Redberg, editor of the
Archives of Internal Medicine, where the studies were
published.
"It's estimated that just from the CT scans done in one year, just
in 2007, there will be 15,000 excess deaths," Redberg said in a
telephone interview.
"We're doing millions of CT scans every year and the numbers are
increasing. That is a lot of excess deaths."
CT scans give doctors a view inside the body, often eliminating the
need for exploratory surgery.
But CT scans involve much higher radiation dose than conventional X-rays.
A chest CT scan exposes the patient to more than 100 times the
radiation dose of a chest X-ray.
About 70 million CT scans were done on Americans in 2007, up from
three million in 1980.
Amy Berrington de Gonzalez of the National Cancer Institute and
colleagues developed a computer model to estimate the impact of so
many scans.
They estimated the scans done in 2007 will cause 29,000 cancers. A
third of the projected cancers will occur in people who were ages
35 to 54 when they got their CT, two-thirds will occur in women and
15% will arise from scans done in children or teens.
The researchers estimated there will be an extra 2,000 excess
breast cancers just from CT scans done in 2007.
Unneeded tests
Redberg, who wrote a commentary on the studies, said US doctors'
enthusiasm for the tests has led to an explosion in their use that
is putting patients at risk.
"While certainly some of the scans are incredibly important and
life saving, it is also certain that some of them were not
necessary," Redberg said.
In a separate study, Dr Rebecca Smith-Bindman of the University of
California, San Francisco, and colleagues analyzed data from 1,119
patients undergoing the 11 most common types of diagnostic CT scans
at four institutions in 2008.
They found radiation dosage varied widely between different types
of CT studies, from a median or midpoint of two millisieverts for a
routine head CT scan to 31 millisieverts for a scan of the abdomen
and pelvis, which often involves taking multiple images of the same
organ.
By comparison, the average American is exposed to about three
millisieverts of radiation a year from ground radon or flying in an
airplane - a level not considered a risk to health.
The researchers said efforts need to be taken to minimize CT
radiation exposure, including reducing the number of unnecessary
tests, cutting the dose per study, and standardizing the doses
across facilities.
Imaging equipment makers such as GE Healthcare, Siemens, Philips
and Toshiba Medical Systems are working to develop low-dose CT
scanners.
