How well do hospital medical technicians know their equipment? Not well enough in the case of some health care workers at Cedars–Sinai Medical Center in Los Angeles, where 206 x-ray computed tomography (CT) scan patients were given eight times the normal dose of radiation during brain scans over an 18-month period. The Los Angeles Times reports today that the cause of the overdoses has been traced back to a mistake the hospital made resetting a CT scanner.

The problem began in February 2008 when the hospital began using a new protocol for CT brain perfusion scans, which expose the brain to radiation in an attempt to help doctors analyze disruptions in the flow of blood to brain tissue and diagnose strokes. This change involved resetting the machine to override the preprogrammed instructions that came with the scanner when it was installed, the Times reports.

"There was a misunderstanding about an embedded default setting applied by the machine," according a written statement issued by the hospital. "As a result, the use of this protocol resulted in a higher than expected amount of radiation." Eight times higher, to be precise.

The error went unnoticed until this August, when a stroke patient informed the hospital that he had begun losing his hair after a scan.

Concerned that this error might not be limited to Cedars–Sinai, the U.S. Food and Drug Administration (FDA) last week issued an alert to CT facilities, radiologists, neurologists and several other types of health care professionals to warn them of possible "widespread problems with CT quality assurance programs," meaning the problem might not be isolated to Cedars–Sinai's equipment or this particular imaging procedure. The alert concluded, however, "While unnecessary radiation exposure should be avoided, a medically needed CT scan has benefits that outweigh the radiation risks."

General Electric, the manufacturer of the scanner, released its own statement Monday saying there were "no malfunctions or defects" of the machine, the Times reports.

©Mikael Häggström via Wikimedia Commons