MELVILLE, N.Y. -- Doctors might be overusing CT scans,
the popular diagnostic tool that exposes patients to far more radiation than
conventional X-rays, scientists in Manhattan will report today.
The analysis by investigators at Columbia University Medical Center comes on the
heels of another released this week by researchers at Brown University, who
found pregnant women are being exposed to twice the amount of radiation through
CT scans as they were in 1997.
Even though the amount of radiation absorbed by pregnant women is still small, a
doubling of the radiation dosage in only a decade is cause for concern, experts
say, because imaging procedures expose the developing fetus to gene-altering
X-rays. Between 1997 and 2006, investigators found the number of imaging studies
of all types performed on pregnant women increased by 121%. The greatest
increases were in the number of CT exams.
In the latest research, reported in today's issue of the New England Journal of
Medicine, Columbia researchers David Brenner and Eric Hall found that the number
of CT scans had increased for everyone over the last 27 years. In 1980, there
were 3 million scans ordered annually in the United States. Now, an estimated 62
million CT exams are performed. The result is a marked increase in the average
personal exposure, which has doubled since 1980.
Hall, a scientist at Columbia's Center for Radiological Research, said the
analysis was driven by a key fact: "We know that radiation causes cancer," he
said of ionizing radiation's capacity to damage DNA, which can lead to
mutations.
Brenner, also a scientist at the center, added that even though a doubling of
radiation exposure had occurred for individuals, that amount of exposure does
not reach a level of alarm. His concern centers on medicine's increasing
reliance on CT scans, which he theorizes could lead to a public health crisis if
usage continues to rise at the current rate.
CT scans, also known as CAT scans, for computerized axial tomography, produce
three-dimensional X-ray images of structures in the body that are quickly taken
in multiples and displayed on a screen. The technology can reveal abnormalities
that are too small or too obscured to be revealed by conventional X-rays. It has
been vital in diagnosing trauma and cancer.
"The radiation dose from a CT scan is far larger than from a conventional
X-ray," Brenner said.
But he said that it had become a indispensable tool for oncology and other
specialized areas of medicine.
He raised questions over so-called defensive medicine."
"One of the most common examples of defensive medicine is when people come to an
emergency room and are given a CT scan even without a diagnosis by a physician,"
he said.
