Study Downplays Risk of CT Scans

Study Downplays Risk of CT Scans

In this photo taken May 4, 2010 a CT is performed on a patient at Cook County Stroger Hospital in Chicago. Americans get the most medical radiation in the world, even more than folks in other rich countries. The U.S. accounts for half of the most advanced procedures that use radiation, and the average American's dose has grown sixfold over the last couple of decades.

By Randy Dotinga
HealthDay Reporter

TUESDAY, May 1 (HealthDay News) -- A new study of young people who underwent CT scans suggests that their risk of dying from a condition related to their radiation exposure is far less than dying from the original disease they faced.

The study has weaknesses, and one specialist said it confirms his belief that the scans are safe but doesn't directly prove it. Still, the lead author of the study said it puts the debate over the safety of CT scans into perspective.

[Read: CT Scans Deliver More Radiation to Obese People.]

"We're trending toward the camp that says you should err on the side of scanning rather than not, because the chance of dying from one to two scans is very small," said study author Rob Zondervan, a medical student at the University of New England. "More often than not, patients should be getting that CT scan because the risk of the underlying cause is higher than from radiation."

Doctors use CT scans to look for signs of trouble in the body from a variety of causes, including cancer, heart, abdominal and lung problems, and trauma from accidents or other injuries. In some cases, patients may get multiple CT scans, even in one day, because doctors are looking for problems in different organs.

Dr. Carl Schultz, a professor of emergency medicine at the University of California-Irvine School of Medicine, said physicians probably order CT scans too much because they're afraid of missing something. "There is no acceptable miss-rate other than zero," he said, "so there's tremendous pressure to do these scans."

In the new study, Zondervan and colleagues examined what happened to more than 23,000 patients aged 18 to 35 who underwent a chest or abdominal CT scan from 2003 to 2007. They all got the scans at three hospitals in Boston.

[Read: Low-Radiation CT Scans Effective at Spotting Appendicitis.]

Of those who got chest CTs, 5 percent to 50 percent of the 8,133 died within a few years, with the rate of death rising sharply in those who got more than one or two scans. The researchers estimate that 12 people in the entire group would have developed cancer because of exposure to scan radiation.

The findings were similar -- with deaths ranging from 2 percent to 33 percent -- in the more than 15,000 who got abdominal CTs. The researchers think 23 people in the entire group would have gotten cancer due to radiation exposure.

"In the patients getting 15 or more scans, all of them had pretty significant disease, where their expected mortality was likely to occur much sooner than the chances of the radiation-induced cancer taking effect," Zondervan said. In other words: Those who were the sickest, requiring the most CT scans, would probably die before any cancer caused by the CT radiation could start hurting them.

Schultz cautioned that the numbers about the possible effects of CT scan radiation are based on assumptions. He added that the study suggests, but doesn't prove, that CT scans save lives.

"I do agree with their premise and their general conclusion that the risk of not doing CTs is greater than doing them," he said.

Still, patients should try to avoid radiation when possible, he said. "Ask whether the same information can be obtained in other way," he said. "In some cases, ultrasound might be better for, say, investigating possible appendicitis."

The findings are scheduled to be released May 1 at the annual meeting of the American Roentgen Ray Society, in Vancouver. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

For more about CT scans, try the U.S. National Library of Medicine.

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