An estimated 206 patients at an unnamed healthcare facility have received CT scan radiation doses that were eight times normal levels, the federal Food and Drug Administration warned.
The agency said yesterday the overdose exposures came about during multi-slice CT imaging to diagnose and treat stroke over an 18-month period. The agency, which said it is investigating the incidents, did not release the hospital's name, location or period of time the excessive radiation doses occurred, saying only that it "has become aware" of the overexposures.
"Instead of receiving the expected dose of .5 Gy (maximum) to the head, these patients received 3-4 Gy (a unit of absorbed radiation dose due to ionizing radiation). In some cases, this excessive dose resulted in hair loss and erythema (redness of skin). The facility has notified all patients who received the overexposure and provided resources for additional information," the agency said.
The FDA called the magnitude of the overdose "significant" and said it may reflect more widespread problems with CT quality assurance programs, "and may not be isolated to this particular facility or this imaging procedure (CT brain perfusion)."
Lower doses of radiation than 3-4 Gy, but which are higher than .5, may not cause obvious radiation injury, but underlying problems "may go undetected and unreported, putting patients at increased risk for long-term radiation effects," the FDA said.
FDA officials added they are "working with the parties involved to gather more data about this situation and to understand its potential public health impact. As FDA obtains more information that better defines the problem, we will be better able to determine if there are more widespread risks."
The notification was distributed to CT facilities, emergency physicians, radiologists, neurologists, neurosurgeons, radiologic technologists, medical physicists, and radiation safety officers.