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:
- Assess whether patients who underwent CT perfusion scans received excess radiation.
- Review radiation dosing protocols for all CT perfusion studies to ensure that the correct dosing is planned for each study.
- Implement quality controls to ensure that dosing protocols are followed every time and the planned amount of radiation is administered.
- Check CT scanner displays to ensure the appropriate radiation level for the patient.
- Ensure that if more than one study is performed on a patient in one imaging session, the radiation dose is adjusted to an appropriate level for each study.
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.
In a statement this week, Cedars-Sinai said it has already implemented many of the FDA's recommendations following an investigation at the medical center. "The FDA's recommendations are similar to the policy and procedure changes that Cedars-Sinai implemented in September after it identified that brain perfusion CT scans were unexpectedly producing higher than expected levels of X-ray radiation," the medical center said in a media release. "Last month, the California Department of Public Health accepted Cedars-Sinai's policy changes as the medical center's plan of correction in response to the department's investigation of the brain perfusion CT scan equipment issue."
It is still not clear who is to blame for the mishap at Cedars-Sinai. Hospital officials previously said they did not want to shift responsibility for the incident to the CT scanner's manufacturer, General Electric. But in its statement last month, Cedars-Sinai officials said the incident "has raised considerable questions about why the manufacturer-set ‘auto' mA setting for the brain perfusion CT scan delivered a higher than expected level of X-ray radiation, since ‘auto' mA settings in CT and other imaging scanners are generally designed to provide the lowest appropriate level of X-ray radiation."
Cedars-Sinai said that nearby Glendale Adventist Medical Center also "reported a similar problem with GE brain perfusion CT scan equipment where patients received higher than expected levels of X-ray radiation."
GE has denied culpability, saying: "Due to pending litigation, we cannot comment on that, but again, there were no malfunctions or defects in any of the GE Healthcare equipment involved in the Cedars incident."
The state's classification of the event as one involving "immediate jeopardy" means that Cedars-Sinai may be subjected to fines of $25,000 to $50,000. Hospital officials have said that about 40% of 206 patients who received doses of radiation either had patches of hair fall out or redness of skin.
Medical center officials also have said that the additional radiation exposure may have made patients more susceptible to cataracts. The hospital has volunteered to pay for any medical expenses caused by conditions related to their overexposures.