Rising use of highly radioactive CT scans has scientists worried
Reported November 29, 2007
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.