A two-year FDA investigation into reports of radiation overdoses in patients undergoing computed tomography (CT) brain perfusion scans has found that operator error, not scanner malfunctions, was the cause. Since it initiated the investigation in 2009, the FDA has discovered at least 385 patients exposed to excess radiation during CT brain perfusion scans.

After investigating those cases, examining the equipment to rule out malfunctions and surveying CT scanner equipment manufacturers, the FDA has determined that the most likely cause of the patient injuries was clinic and hospital negligence in training technicians and radiologists on the proper administration of CT brain perfusion scans.

A CT brain perfusion scan is only one type of CT scan, and not all CT facilities provide it. The scan produces images of cross-sections of the brain to evaluate blood flow.

CT scans, X-rays, fluoroscopy and nuclear medicine procedures use ionizing radiation to produce images. Patients who receive an excessive dose of ionizing radiation may experience an increased lifetime risk of cancer or immediate, visible symptoms such as burns and hair loss. If the excess exposure is directed at the eyes, the patient can have an increased risk of developing cataracts.

When correctly operated, CT scans do not expose patients to dangerous levels of ionizing radiation, and the FDA emphasizes that the benefits of medically necessary CT scans outweigh the normal radiation risks. Patients should follow their doctors’ recommendations about getting CT scans.

FDA Recommends Steps to Promote Patient Safety and Reduce the Incidence of Improper Operation of CT Scanners

Because CT scanners generally do not malfunction and, when properly used, CT brain perfusion scans do not expose patients to unduly high levels of radiation, the FDA has recommended steps to reduce the risks. The recommendations are intended to improve operator training and reduce the radiation risk even if CT scanner technician or radiologist negligence does occur.

The FDA recommendations include:

• Posting a notice to alert the technician or radiologist that there is a risk of a high radiation dose
• Posting clear instructions on how to appropriately set the radiation dose parameters, along with clarification of the appropriate dose parameters
• Organizing all dose-related information into a single manual or a single section of the user manual, or comprehensively indexing dose information across different types of manuals
• Providing training on brain-perfusion protocols to all facilities with CT scanners, whether or not they perform CT brain perfusion tests

Because patients experiencing low to moderate overdoses of radiation may not show symptoms, it is not known how many patients have been exposed to excess radiation during CT scans.

“Improving patient safety is part of our public health mission,” says the director of the FDA Center for Devices and Radiological Health, Dr. Jeffrey Shuren. “Patients should not have to worry that a device designed to diagnose an illness exposes them to unnecessary risks.”

Sources:

• ConsumerAffairs.com, “Feds Probe CT Scan Radiation Overdoses,” James Limbach, November 11, 2010
• U.S. Food and Drug Administration, “Questions & Answers: Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging”