Because children and adolescents are particularly vulnerable to radiation, doctors three years ago mounted a national campaign to protect them by reducing diagnostic radiation to only those levels seen as absolutely necessary. Not only do most dentists continue to use outmoded X-ray film requiring higher amounts of radiation, but orthodontists and other specialists are embracing a new scanning device that emits significantly more radiation than conventional methods, an examination by The New York Times has found. Some orthodontists now use cone-beam CT scans to screen all patients, even though a number of dental groups in this country and in Europe have questioned whether the benefit of routine use justifies the added risk. The cone-beam business is lucrative for manufacturers and dentists. According to one industry estimate, more than 3,000 scanners and about 30 different models have been sold, at prices up to $250,000.
Dentists, some of whom charge several hundred dollars per scan, can profit by owning their own machines. “More profit per unit chair time,” promises Imaging Sciences, the cone-beam manufacturer. The company’s i-CAT scanner is one of the most popular on the market.
“I use my i-CAT for everything,” one orthodontist, Dr. Edward Y. Lin, proclaimed in a full-page advertisement in one magazine.
Whatever the radiation levels from a particular cone-beam scan, the risk is small, said Dr. Brenner, the Columbia University radiation researcher. But it is only worth taking, he said, if there is demonstrable benefit, particularly for young patients who are “typically 5 to 10 times more sensitive than adults.”
Dr. Brenner said that a child faces up to a 1-in-10,000 chance of developing cancer from a single cone-beam scan. Yet orthodontic patients frequently get more than one scan during treatment and face a lifetime of additional X-rays, all of which scientists believe are cumulative. “You double the dose, you double the risk,” Dr. Brenner said