Excessive CT scans pose radiation risk: doctors

Excessive CT scans pose radiation risk: doctors
BOSTON (Reuters) - They save lives and speed diagnosis butthe 62 million CT scans done in the United States each year maysoon be responsible for 2 percent of all cancers, tworesearchers said on Wednesday.
Because doctors underestimate the radiation risk fromcomputed tomography or CT scans, a type of souped-up X-ray,they may be ordering too many of the scans, David Brenner andEric Hall of Columbia University Medical Center in New Yorksaid.
They also said a straw poll of physicians has suggestedthat perhaps one-third of the scans may be unnecessary or couldbe replaced by an alternative technique, such as ultrasound.
"If it is true that about one-third of all CT scans are notjustified by medical need, and it appears to be likely, perhaps20 million adults and, crucially, more than 1 million childrenper year in the United States are being irradiatedunnecessarily," they wrote in a commentary in the New EnglandJournal of Medicine.
But they acknowledged in a telephone briefing that theassertion is a "back of the envelope" estimate based on theimpressions of doctors. They said no study has tried to gaugethe problem of unnecessary CT scans.
A typical CT scan can deliver 50 to 100 times moreradiation than a conventional X-ray, depending on the sitebeing examined and the age and brand of the machine.
Children have a higher risk from the scans because theirtissues are at least 10 times more sensitive to radiation. Inaddition, long-term side effects have more time to appear.
"We were astonished to find when we were researchingmaterial for this paper how many doctors, particularlyemergency room physicians, really had no idea of the magnitudeof the doses or the potential risk that it would involve," saidHall.
"It has been estimated that about 0.4 percent of allcancers in the United States may be attributable to theradiation from CT studies. By adjusting this estimate forcurrent CT use, this estimate might now be in the range of 1.5to 2.0 percent" once tumors from current exposures begin toappear, they wrote.
Brenner and Hall said ultrasound and magnetic resonanceimaging, or MRI, scans should be used instead of CT scanswhenever practical. CT scans are particularly overused inlooking for childhood appendicitis, they said.
Other solutions may include developing systems fordiscouraging doctors from performing unnecessary CT scans,reusing scans if patients are sent to another doctor orhospital, and urging patients -- or their parents -- to askabout the radiation risk involved in a CT scan, a questionthat, in itself, is likely to make doctors think twice.
But Fred Mettler of the University of New Mexico inAlbuquerque said one reason doctors are quick to order a CTscan is that it can quickly spot a variety of potentialproblems that could be missed by other tests.
"It's a huge efficiency issue," Mettler told reporters onthe briefing.
Nonetheless, "I've seen people who are 30 years old who hadat least 18 scans done. So this is a big problem," he said.
(Editing by Maggie Fox and Bill Trott)