In response to highly publicized mishaps and ongoing concerns that patients are being subjected to excess radiation during CT scans, the FDA this week issued interim recommendations to help prevent additional problems.
"While we do not know yet the full scope of the concern, facilities should take reasonable steps to double-check their approach to CT perfusion studies and take special care with these imaging tests," Jeffrey Shuren, MD, acting director of the FDA's Center for Devices and Radiological Health, said in a media release.
An initial safety notification was issued by the FDA in October after learning of 206 patients who had been exposed to excess radiation at Cedars-Sinai Medical Center in Los Angeles over 18 months. Since then, the FDA has identified at least 50 additional patients who were exposed to excess radiation of up to eight times the expected level during their CT perfusion scans. These cases so far involve more than one manufacturer of CT scanners. The FDA has also received reports of possible excess radiation from other states. Some of these patients reported hair loss or skin redness following their scans.
The settings on Cedars-Sinai's three CT scanners were changed, causing "immediate jeopardy" in a case that the hospital says involved 206 patients who underwent stroke imaging between February 2008 and September 2009, according to a report released in November by California health officials.
The report said that "on or about February 2008, the scanning parameters of three CT Scanners were changed from the manufacturer's recommended output of 80 kv (the amount of voltage delivered) and 200 mA (milliampere, the duration of the exposure) to 120 kv and 'automatic,' meaning the machine determined mA (usually in the 500 mA range)."
As a result of its own investigation, the FDA issued interim recommendations for imaging facilities, radiologists, and radiologic technologists to help prevent additional cases of excess exposure. These recommendations apply to all CT perfusion images, including brain and heart.
The FDA recommends that CT facilities:
The FDA is also working with manufacturers, professional organizations, and state and local public health authorities to investigate the scope of these excess exposures, and is asking manufacturers to review training for users, reassess information provided to healthcare facilities, and put into place new surveillance systems to identify problems quickly.