The FDA yesterday issued interim recommendations in response to the ongoing investigation of radiation overexposure at Cedars-Sinai Medical Center in Los Angeles.

The agency issued an initial safety notification in October, after discovering that 206 patients at the Los Angeles hospital had received excess radiation during CT perfusion brain scans over a period of 18 months. Yesterday, the FDA also revealed that in working with state and local health authorities, it 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.”

Previously, GE Healthcare had been identified as the manufacturer of the scanners involved in the radiation overexposure cases, but, according to the FDA, the cases now involve more than one manufacturer.

Last month, the Los Angeles Times reported that the radiation overexposure problem extended beyond Cedars-Sinai to Glenville Adventist Medical Center, a small hospital in Los Angeles County. According to the Times, 10 patients undergoing CT scans there earlier this year received radiation doses three to four times that of the normal radiation dose.

The FDA also noted it has received reports from other states of possible cases of exposure due to excess radiation.

"The FDA is making progress in the investigation of this problem," said Jeffrey Shuren, MD, acting director of the FDA’s Center for Devices and Radiological Health. “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."

The interim recommendations are meant for imaging facilities, radiologists and technologists, and apply to all CT perfusion imaging, including for the brain and heart because they use similar protocols and procedures. The FDA recommended that:

• Facilities assess whether patients who underwent CT perfusion scans received excess radiation.
• Facilities review their radiation dosing protocols for all CT perfusion studies to ensure that the correct dosing is planned for each study.
• Facilities implement quality control procedures to ensure that dosing protocols are followed every time and the planned amount of radiation is administered.
• Radiologic technologists check the CT scanner display panel before performing a study to make sure the amount of radiation to be delivered is at the appropriate level for the individual patient.
• If more than one study is performed on a patient during one imaging session, practitioners should adjust the dose of radiation so it is appropriate for each study.

The FDA said it is also recommending that manufacturers review their training for users, reassess information provided to health care facilities and establish new surveillance systems to identify problems quickly.