When patients began asking Cmdr. Alexander Stewart, MD, an attending physician in otolaryngology head and neck surgery at San Diego’s Naval Medical Center, about risks from CT scan radiation, he realized he didn’t know enough to answer with authority. “What’s the dose I’m recommending? What’s the risk? I really didn’t know,” he admitted.
Explore this issue:September 2012
As he tackled the literature to learn more, Dr. Stewart learned he wasn’t alone. A review of physician knowledge about CT radiation doses and risks showed the majority of doctors surveyed were on shaky ground (Eur J Radiol. 2010;76(1);36-41). He also read about variability in doses with the same type of scan and decided to do his own study. “The impetus was to educate specialists, our ENTs, about it,” he said.
Dr. Stewart worked with a radiologist and a radiological physicist to take measurements from a variety of in-office, hospital-based and outpatient imaging facility CT scanners used by otolaryngologists for sinus scans and found a 10-fold difference in radiation doses delivered (Int Forum Allergy Rhinol. 2011;1(4):313-318). The machines themselves were not the main factor in the variability measured, he said. “It’s the input into the machine—the protocols—that’s what’s variable.” Further, he said, manufacturer’s guidelines are typically optimized for the best image, not for keeping radiation doses as low as reasonably achievable—ALARA.
Legal regulations to report and track radiation exposure from medical tests may also come into play. In California, for example, a new law requires the reporting of radiation dose for every procedure.
What Can Practitioners Do?
In addition to educating themselves and taking the time to talk through the risks and benefits of CT scans with patients and their parents, otolaryngologists should collaborate with their radiologist colleagues. “They’re your local experts on radiation safety and doses. They’re the most familiar with [scanner] protocols,” Dr. Stewart said.
Lower doses are indicated for children. Dr. Hanley said some machines have a “pediatric button,” which is too nonspecific to be useful. “There’s a big difference between a 2-year-old and a 16-year-old,” he said. “One size doesn’t fit all.”
Other local resources include hospital radiation physicists, who are responsible for quality assurance, and even the technologist who works the scanner. “A lot of things can be done at the technologist level,” said Dr. Hanley.
Scanner manufacturers are working on the issue, Dr. Hanley added. “From the industry side, all the buzz is how to reduce dose.” The two main strategies used are scanning faster and boosting the software’s ability to reconstruct images.