FDA Scrutinizes Medical Radiation Exposure


Yesterday, the U.S. Food and Drug Administration announced it would diligently address ways to reduce unnecessary radiation exposure from three powerful types of  medical imaging: computed tomography (CT), nuclear medicine studies, and fluoroscopy. These procedures are responsible for most of the total radiation exposure within the United States and use much higher doses than other radiographic measures, such as standard X-rays, dental X-rays, and mammography. Some CT scans emit radiation equal to 400 chest X-rays.

CT, nuclear medicine, and fluoroscopic imaging have augmented early diagnosis of disease, aided treatment planning, and image-guided therapies that help prolong lives. CT scans provide three-dimensional images; in nuclear medicine studies, patients are given a radioactive substance while doctors watch it move through the body; with fluoroscopies, a radiation-emitting device reveals a constant internal image on a monitor.

All medical procedures, including CT, nuclear medicine, and fluoroscopy entail risks. These types of imaging endanger patients to ionizing radiation, which can increase a person’s chance of cancer. Accidental exposure to high amounts of radiation can cause injuries, such as skin burns, hair loss and cataracts.

“The amount of radiation Americans are exposed to from medical imaging has dramatically increased over the past 20 years,” said Jeffrey Shuren, M.D., J.D., director of the FDA’s Center for Devices and Radiological Health. “The goal of FDA’s initiative is to support the benefits associated with medical imaging while minimizing the risks.”

The FDA has been probing why more than 300 patients in four hospitals were overradiated by CT scans used for stroke detection. The overdoses were initially revealed last year at Cedars-Sinai Medical Center in Los Angeles, when patients received up to eight times more than the prescribed radiation, according to The New York Times. The time span was 18 months and errors uncovered only after patients lost their hair.

While there is debate over the cancer risk associated with radiation exposure from medical imaging, there is agreement that reducing unnecessary radiation exposure is imperative. For example, a dental X-ray uses about one-half the dose of a chest X-ray.

Through the FDA’s regulatory oversight of medical imaging devices and through collaboration with other federal agencies and health care professional groups, the FDA is advocating adoption of two principles of radiation protection: Appropriate justification of the radiation procedure and optimization of the radiation dose used during each procedure. “Working together,” saidDr. Jeffrey Shuren, director of the F.D.A.’s Center for Devices and Radiological Health,“the FDA and other organizations hope to help patients get the right imaging exam, at the right time, with the right radiation dose.”

Among the proposals under consideration: that devices display, record and report equipment settings and radiation dose; that an alert be issued when the radiation dose exceeds an optimal dose for most patients; and that devices be required to capture and transmit radiation dose information to a patient’s electronic medical record and to national dose registries.

“I think it is very timely in light of concerns about radiation exposure and the possibility of overexposure,” said Dr. James Thrall, professor of radiology at Harvard Medical School and chairman of the American College of Radiology. “I think it will nudge the industry,” quoted the Times.

A major issue, Dr. Thrall said, is that “there is nothing on the machine that tells the technologist that they’ve dialed in a badly incorrect radiation exposure.”

Unfortunately, some states are not mandated to report radiation accidents involving CT scans, fluoroscopy equipment and radiotherapy devices.