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Medical alarm over increase in CT scans, and the risks of cancer

Physicians are not required to inform patients in writing about the radiation risks of CTs. But Dr. Richard Semelka, director of MRI services at the University of North Carolina at Chapel Hill, said the time has come for that to change.

“It should be abundantly clear by now that ionizing radiation does carry with it the risk of cancer,”

Use of imaging tests soars, raising questions on radiation risk,, Study finds use of CT scans has nearly tripled in the last 15 years. Such radiation exposure increases the risk of cancer. By Jon Bardin, Los Angeles Times June 13, 2012
The use of CTs, MRIs and other advanced medical imaging tests has soared over the last 15 years, according to new research that raises questions about whether the benefits of all these scans outweigh the potential risks from radiation exposure and costs to the healthcare system.

An examination of data from patients enrolled in six large health
maintenance organizations found that doctors ordered CT scans at a
rate of 149 tests per 1,000 patients in 2010, nearly triple the rate
of 52 scans per 1,000 patients in 1996…….
These and other tests have meant that more patients have absorbed more
ionizing radiation as part of their medical care. The proportion of
patients in the study who had any amount of radiation exposure —
driven by the use of CTs — rose from 28.5% in 1996 to 36.2% in 2010;
among them, their average exposure jumped from 4.8 millisieverts to
7.8 millisieverts. At the top end of the spectrum, the proportion of
patients in the study who got radiation at high or very high levels
rose from 1.8% to 3.9%.

“We’ve become victims of our own technology,” said Dr. George Bisset,
chief of pediatric radiology at Texas Children’s Hospital in Houston
and president of the Radiological Society of North America.
Advances in imaging technology have allowed doctors to peer inside the
body with striking resolution. Computed tomography, or CT, scans
combine a series of X-rays into a detailed three-dimensional image.
Magnetic resonance imaging machines detect energy emitted by hydrogen
atoms in the body and convert that into pictures. Both tests can
reveal blockages in arteries, bleeding in the brain, tumors and other
life-threatening conditions.

Although MRIs do not use ionizing radiation, CTs do, and that can
damage the DNA in cells and lead to mutations that cause cancer. A
number of recent studies have linked increases in medical imaging to
higher rates of radiation-induced cancers, including a report last
week in Lancet that showed a correlation between CT scans in children
and their subsequent risk of developing brain tumors or leukemia.

And both kinds of tests are expensive. Advanced imaging adds about
$100 billion to U.S. medical bills each year, said study leader
Rebecca Smith-Bindman, a radiologist and epidemiologist at UC San
Francisco.

There is widespread agreement in the medical community that imaging
tests are overutilized, particularly CT scans. In April, the American
Board of Internal Medicine released a report that asked doctors from
numerous medical specialties to list five procedures they felt were
used too much. All of the doctors — including cardiologists,
oncologists and family physicians — listed CT scans among their top
five.

Researchers have already charted similar growth in advanced imaging in
fee-for-service medical systems, where doctors may have a financial
incentive to order tests that aren’t really necessary.

The JAMA report is the first large study to focus on imaging use in
HMOs. The findings suggest that profit-seeking on the part of doctors
is not the primary cause of the increase in testing……
Experts said they were most concerned by the growth in CT use
documented in the study. The researchers found that 2.5% of the
patients in the six HMOs were exposed to between 20 and 50
millisieverts of radiation in 2010, a level that the International
Commission on Radiological Protection says is unsafe. Another 1.4% of
the patients were exposed to more than 50 millisieverts of radiation
that year, which the U.S. Nuclear Regulatory Commission says is
dangerous.

In an editorial that accompanied the study, two physicians wrote that
these high doses should prompt doctors to consider the radiation risks
of the tests they order and discuss those risks with their patients.

Physicians are not required to inform patients in writing about the radiation risks of CTs. But Dr. Richard Semelka, director of MRI services at the University of North Carolina at Chapel Hill, said the time has come for that to change.

“It should be abundantly clear by now that ionizing radiation does carry with it the risk of cancer,” said Semelka, who wasn’t involved
in the study. “It just seems so obvious that we should be providing
patients with the risks even if we don’t have the exact numbers.”
http://www.latimes.com/news/science/la-sci-ct-mri-growth-20120613,0,641613.story

June 13, 2012 - Posted by Christina Macpherson | health, USA