Federal health regulators are investigating reports of dangerous radiation levels at two more California hospitals, following earlier unsafe medical scans at a Los Angeles facility.
The Food and Drug Administration is probing the use of CT scans at Glendale Adventist Medical Center and Providence St. Joseph Medical Center in Burbank, Calif. The brain scans are used to diagnose strokes.
FDA officials told reporters Monday that they are investigating at least 10 reports of excessive radiation at Glendale Adventist and an unspecified number of problems at St. Joseph.
A spokeswoman for Glendale Adventist said the problems, first disclosed last month, were related to a specialty scan that involves three different techniques.
"This procedure has been discontinued," Alicia Gonzalez said in a statement.
A spokeswoman for St. Joseph Medical center had no immediate comment.
The FDA began looking into problems with CT scanning in October after patients at Cedars-Sinai Medical Center in Los Angeles reported losing hair or skin redness. The hospital last month said 260 patients were exposed to excess radiation, up from prior reports of 206.
A Cedars-Sinai spokeswoman said the hospital continues to work with the FDA to identify the cause of the problems.
FDA officials say it's unclear whether the dangerous exposures are being caused by human error or a problem with CT equipment.
Cedars-Sinai and Glendale Adventist both use scanners from General Electric. But FDA officials said they have received reports of problems at other hospitals using different brands of scanners, including models from Toshiba.
GE spokesman Arevind Gopalratnam said in a statement "there were no malfunctions or defects in any of the GE Healthcare equipment involved." He added that the company is cooperating with the FDA's investigation.
Agency officials said they also are investigating reports of dangerous CT scanning in Huntsville, Ala., although they did not specify a hospital.
The FDA urged all hospitals and medical facilities to review radiation dosing guidelines to make sure procedures are followed for each scan. Officials have also advised manufacturers to review their training for CT scanner operators.
"While we do not know yet the full scope of concern, the facilities should take reasonable steps to double-check their approach to CT perfusion studies and take special care with these imaging tests," said Dr. Jeffrey Shuren, acting director of FDA's Center for Devices and Radiological Health.
The average American's total radiation exposure has nearly doubled since 1980, largely because of CT scans, according to recent studies. Medical radiation now accounts for more than half of the population's total exposure; it used to be just one-sixth.
The risk from a single CT scan is small, but overexposure can increase the risk of cancer.
CT scans became popular because they offer a quick, relatively cheap and painless way to get three-dimensional pictures so detailed they give an almost surgical view into the body. Doctors use them to evaluate trauma, belly pain, seizures, chronic headaches and other woes.
(This version CORRECTS throughout that new reports are not from Cedars-Sinai.)