The 206 people who received "significant" overdoses of radiation eight times above expected levels were undergoing CT scans for detection of stroke at Cedars -Sinai Medical Center in Los Angeles, federal and hospital officials confirmed on Friday.
The incidents, which may have occurred over an 18-month period starting in February 2008, is under investigation by California public health officials and the U.S. Food and Drug Administration.
The multi-slice CT scanner involved was manufactured by GE Health Care, said Mary Long, spokewoman for the FDA. "We are evaluating information to determine if this is a more widespread problem with CT protocols and not limited to one facility or scan," she said. The FDA wants hospitals that may have had similar problems with such scans to file a voluntary report to the agency's Medwatch Web site.
"We are collecting information from the manufacturer and the facility relating to both the equipment and its use," she added.
Sandy Van, spokesman for Cedars-Sinai, said the problem was noticed in August 2009, "when a patient who had previously received a scan contacted the medical center after noticing temporary patchy hair loss.
"Since this is not a common side-effect from CT brain perfusion scans, Cedars- Sinai immediately began an investigation of the equipment involved and the protocols used for CT brain perfusion scans," Van said in a statement. "No additional CT brain perfusion scans were done until the investigation was completed."
Van did not answer a question about how many patients had experienced symptoms linked with radiation overdose, but according to a Los Angeles Times article on Saturday, a hospital spokesman said about 40% of the patients lost patches of hair as a result of the overdoses. It is unclear why the problem with the scans was not recognized until August.
GE Healthcare said in a statement "there were no malfunctions or defects in any of the GE Healthcare equipment involved in the incident."
They emphasized that "patients and families should continue to have confidence in their doctor's recommendation for a CT scan."
Also, the company said GE "continues to offer dose-reducing technologies and expand key CT training initiatives to raise awareness of dose optimization and use of appropriate exam protocols.
"GE Healthcare CT products require that: 1) users carefully evaluate user-defined scanning protocols against the validated protocols that are provided on the scanners during installation, 2) like dose recommendations for drugs, the recommended dose for a prescribed medical imaging scan is an important clinical decision that should be made by a licensed professional in the context of healthcare delivery."
The investigation revealed that some scans "were delivering a higher dose of radiation than anticipated, which could cause temporary hair-loss or skin-reddening in some patients," Van said.
Additional double-checks and equipment protocols have been instituted "to ensure that this does not happen again."
Van said that although the hair loss or skin reddening would have occurred within six weeks of the scans, the hospital contacted 206 patients who had a scan between February 2008 and August 2009 in the interest of keeping those patients informed.
The problem also was reported to the California Department of Public Health as an unusual event.
The FDA said in an initial notice about the patient over-exposure that "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's Long emphasized that the FDA wants every facility that performs CT imaging to review its protocols "and be aware of the dose indices normally displayed on the control panel. These indices include the volume computed tomography dose index (abbreviated CTDI in units of "milligray" or "mGy") and the dose-length product (DLP, in units of milligray-centimeter" or "mGy-cm").
The warning continued to say that for each protocol selected and before scanning each patient, "carefully monitor the dose indices displayed on the control panel. To prevent accidental overexposure, make sure that the values displayed reasonably correspond to the doses normally associated with the protocol. Confirm this again after the patient has been scanned."
Cedars-Sinai officials also were not able to say what level of multi-slice machine or machines were linked to the overdoses. It also is unclear whether the patients are at increased risk of cancer or other medical problems months or years later.
They also did not explain whether the malfunction was caused by the protocol or the machinery itself. Cedars-Sinai officials did not say whether the patients are undergoing any follow-up care or whether they have received any compensation for any harm or risk of harm they may endure.
Cedars-Sinai is certified by the Joint Commission as a primary stroke center. It is listed as one of the U.S. News and World Report's best hospitals in 11 categories, including neurology and neurosurgery.