A new type of sophisticated diagnostic device gives dentists a futuristic view of your jaw, but exposes patients to much more radiation than they get from conventional X-rays.
The New York Times reports that dentists and orthodontists are all agog for cone-beam CT scanners, which replace the traditional X-rays with “brilliant,” three-dimensional images of everything that interests: cavities, tooth decay, even detailed pictures of the skull.
Yet each time they are used, the cone-beam scanners give patients a dose of radiation up to 67 times greater than what patients receive from X-rays.
While the threat posed by a single cone-beam scan is small for patients (a roughly 1-in-10,000 risk of cancer, according to Dr. David Brenner, a Columbia University radiation researcher), the risks escalate when the next visit to the dentist means a new scan and, consequently, another radiation bath.
Some experts say that while the cone-beam scanner can be helpful in diagnosing complicated problems, the practical improvement over traditional X-ray methods in most cases is unproven. They also say the cone-beam scanners are more popular in large part because of the sense that they are high-tech.
“Kids love to see that 3-D image,” said Dr. Terry Sellke, an orthodontist in Illinois. “They can go into our computer and look at their skull.”
The various manufacturers of cone-beam devices have been aggressive about promoting them to dentists and orthodontists. They advertise in trade magazines–“I use my i-CAT for everything,” proclaims one testimonial, in reference to a popular cone-beam model. Last month, The Journal of the American Dental Association allowed one of the leading manufacturers to underwrite an issue focused entirely on cone-beam technology. And six manufacturers spent $290,000 to promote their products at an American Dental Association conference last month, according to The Times.
Beyond marketing, one of the reason the cone-beam scanners have become so popular is because they translate into an instant increase in revenue for dentists and orthodontists. One orthodontist who spoke with the Times said that the time saved by using the cone-beam scanner with his patients gave his practice an added $150,000 per year.
The savings encourages using the scanners even when a lower-radiation substitutes would work just as well. This problem is compounded by extremely lax regulation. “Some states have in effect no inspections of dental X-ray units,” said Dr. G. Donald Frey, professor of radiology at the Medical University of South Carolina. “States tend not to want to regulate the practice of medicine or dentistry.”
Even dentists who continue to rely on conventional X-ray devices in most cases use an outmoded type of X-ray film that provides more radiation exposure than necessary. Though dentists have been advised to abandon slow, D-speed film for performing X-rays, most have not switched to faster film that reduces the radiation dose, The Times reports.
Compared to doctors, dentists have also shown less of an inclination to self-regulate. While American doctors embarked on a nationwide campaign to lower radiation exposure for children and teens, nothing comparable has occurred in dentistry.
http://www.xrayrisk.com has more info on radiation and cancer risk including an online calculator that lets you calculate radiation dose and estimate cancer risk from CT scans, x-rays and procedures. The site also allows users to log-in and track their imaging history.