The U.S. Food and Drug Administration (FDA) said that it has found additional cases of radiation overexposure related to CT brain perfusion scans. The new cases occurred at hospitals besides Cedars-Sinai Medical Center in Los Angeles and involve more than one CT manufacturer.
In a December 7 news conference, the FDA updated the media on the status of its investigation and gave healthcare providers guidance on steps to take to reduce unnecessary radiation during CT scans. The news conference was a follow-up to a news story that broke in October, when the agency said it was looking into a case in which 206 patients received up to eight times the recommended radiation dose at Cedars-Sinai.
The patients were scanned on equipment manufactured by GE Healthcare of Chalfont St. Giles, U.K., but the scanning protocol apparently was developed by Cedars-Sinai healthcare staff.
Since then, the FDA has discovered additional patients at Cedars-Sinai who received excessive exposure, bringing the total to 250. What's more, the agency has received a report of 14 patients who were overexposed at Glendale Adventist Medical Center in Glendale, CA, as well as a similar report from Providence St. Joseph Medical Center in Burbank, CA. Finally, the FDA has received reports of overexposures in other states, such as Alabama.
Some of the new reports involved GE scanners, but the agency said that at least one overexposure case involves a scanner manufactured by Toshiba America Medical Systems of Tustin, CA. The agency did not say which facility used the Toshiba system.
The FDA declined to comment on whether its investigation indicated that the overexposure cases were caused by human error in operating the scanners, or if there were basic flaws in the CT systems that caused the incidents. Until then, the agency is recommending that CT sites take extra vigilance in setting their scanning protocols, and it provided several recommendations:
- Imaging facilities that perform CT perfusion scans should assess whether patients who have received CT perfusion scans have received excess radiation.
- Facilities should review their radiation-dosing protocols for all CT perfusion studies to ensure that the correct dosing is planned for each study.
- Facilities should implement quality control procedures so that dosing protocols are followed every time and the planned amount of radiation is administered.
- Radiologic technologists should check CT scanner display panels before performing a study to make sure that the correct radiation dose will be used.
- If more than one study is performed during one imaging session, practitioners should adjust the dose of radiation so that it is appropriate for each study.
While the recommendations might seem self-evident, healthcare facilities can sometimes lose track of radiation dose over time when using specially developed scanning protocols, said Dr. Jeffrey Shuren, acting director of the FDA's Center for Devices and Radiological Health.
"What happens over time is that facilities may wind up using particular algorithms that will then calculate the radiation exposure for a particular test," Shuren said. "Sometimes those algorithms are designed to encapsulate multiple tests. What we are suggesting here is that until such algorithms are validated, make sure it is the proper dose for that particular patient before initiating the study."
A representative from GE Healthcare said that its internal investigation has found no malfunctions or defects in any of the scanners involved. The Alabama case, at Huntsville Hospital in Huntsville, was the result of "a medical decision made by the staff there," and the GE scanners at the facility are "operating as intended."
"As with all CT head perfusion scans, the radiation dose delivered was a decision made by healthcare providers during the treatment of stroke patients," a GE statement said. "Patient safety continues to be the primary concern of Huntsville Hospital, and GE Healthcare will continue to support in providing user training on dose-reducing technologies and methods."
Meanwhile, a Toshiba spokesperson said the company is cooperating with the FDA investigation.
"The FDA has informed us of one site where potential overradiation has occurred on a Toshiba system," the spokesperson said. "We are cooperating fully with the FDA and working with them to investigate this matter."
By Brian Casey
AuntMinnie.com staff writer
December 7, 2009
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