Doctors are exploring ways to reduce the amount of radiation exposure from medical imaging tests in light of renewed concerns about the cancer risk, according to research presented at a radiology conference this week.
Medical radiation from exams such as CTs, or computed tomography, causes 29,000 new cancers a year, a report in the Archives of Internal Medicine showed in December. An accompanying article found that the scans may expose people to four times as much radiation as previously estimated. The Food and Drug Administration is considering safeguards for CT scanners and other imaging machines.
"It's a very serious issue," says radiologist Sobhi Abadi of McGill University in Montreal, who presented his research Tuesday at a meeting of the American Roentgen Ray Society in San Diego.
Radiologists have been working for several years to reduce unnecessary radiation exposure in children, whose growing bodies are more sensitive to radiation than adults', says Richard Morin, chairman of the American College of Radiology's Safety Committee. Later this year, he says, radiologists will expand the effort to adults.
But Morin says other doctors also need to do more to protect patients, such as referring them for imaging tests only when they're really necessary. Studies show that one-third of CT scans aren't medically needed but are performed because of fear of lawsuits, among other reasons.
Abadi's study focused on reducing the risk of future breast cancer in women who have heart scans.
The heart scans, called CT coronary angiography, allow doctors to examine the arteries around the heart without surgery, Abadi says. They're increasingly being used in younger women -- those in their 40s and 50s -- who have a greater lifetime risk of developing radiation-related breast cancers because they have many years left to live.
Abadi reduced radiation to the breast by more than 80% using two methods. First, he used a technique that allows radiologists to scan only during a certain phase of the heartbeat cycle. Second, he covered breasts with a shield to block out X-rays, says Abadi, who wrote his paper while at the University Health Network in Toronto. Together, the two techniques reduced the radiation dose from 83 milligray -- equal to about 27 mammograms -- to 12 milligray, equal to about four mammograms.
Morin notes that breast shields are controversial because some doctors are concerned that they could block X-rays from leaving the body.
Other presentations showed that doctors could safely give less radiation during each exam, either by using a special filter or by making adjustments for patients' age, weight and the reason why they need the procedure.
Radiologist Rebecca Smith-Bindman, whose research found that patients are getting more radiation during CT scans than previously estimated, applauded doctors who have found ways to protect patients from unnecessary exposure. But patients would be even better off if the USA had more comprehensive, uniform standards aimed at reducing radiation, she says.
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