October 3, 2007

Too much of a good thing?
Radiology chief cautions
colleagues on CT scanning

Delivering more than 100 times the radiation of a chest X-ray,
computed tomography (CT) scans are potent tools with a downside.

James Brink, chair of Diagnostic Radiology, thinks that doctors should consider a variety of factors before ordering CT exams for their patients.

Computed tomography (CT) scans, which are used to identify everything from brain tumors to the reason for a patient’s acute abdominal pain, are an invaluable diagnostic tool, but too much exposure to the radiation they use could increase a patient’s risk of cancer, according to a Yale physician.

James A. Brink, professor and chair of diagnostic radiology, says physicians need to be more aware of the risks posed by CT and other imaging devices that rely on radiation. “America has been behind in this topic for some time,” says Brink. “When I visit other countries, there’s much more awareness and concern about the danger of low-dose exposure to radiation.”

The number of CT scans administered annually in the United States has grown from 3 million in 1981 to 63 million in 2005.  In terms of radiation exposure, one CT scan is equal to between 100 and 250 chest X-rays. Patients are sometimes subjected to many CT scans, and the cumulative radiation can be so high as to equal that of a medium-dose exposure to the radiation released by an atomic bomb.

Brink would like to see physicians order fewer CT scans, particularly when they’re used for such purposes as to rule out kidney stones in patients with flank pain, or for patients, particularly young women, suspected of having pulmonary embolism. He suggests the following ways to limit patients’ exposure to the low-dose radiation from CT imaging:

• Avoid ordering CT scans when an X-ray, MRI or ultrasound will be sufficient.
• Be sure repetitive CT scans are medically necessary.
• Avoid exposing the patient to more radiation than necessary by tailoring the scan. A CT for kidney stones, for example, uses less radiation than one for metastatic colon cancer.
• Education. If physicians are aware of the health risks associated with CT radiation, they’ll take steps to avoid or reduce patients’ exposure. (A 2004 study conducted by Brink and colleagues found that only 9 percent of emergency physicians who had ordered CT scans for pelvic pain over a two-week period thought the test posed an increased cancer risk.)

A full body scanner in the department's CT suite is used for routine CT studies as well as cardiac CT imaging and bone biopsies.

In the United States, medical necessity and a physician’s judgment determine whether a CT is approved; radiation exposure isn’t part of the equation. This differs dramatically from the way CT imaging is handled in Europe, according to Brink. Several years ago, the Council of the European Union issued a directive to member countries establishing guidelines for the use of medical radiation. Those guidelines, which were passed into law in many countries, spell out the responsibilities referring physicians and radiologists have when ordering CT scans. Brink believes a similar system may be needed here if physicians don’t self-regulate.

“Don’t get me wrong,” he says. “CT is a phenomenal technique that is used all the time all over the world to make and rule out diagnoses. I’m not saying it shouldn’t be used. I’m just saying we have to use it judiciously.”

—Jill Max

Photos by Henry Douglas

Subscribe