Return to basics needed to prevent excess radiation from CT scans

FDA officials issued interim guidelines, today, as part of an ongoing investigation after reports earlier this year that more than 200 patients at Cedars-Sinai Medical Center in Los Angeles were exposed to excess radiation during CT perfusion scans.

Involved patients have reported hair loss and skin redness. High doses may cause cataracts and increase the risk for some forms of cancer, according to the FDA.

“Although we continue to investigate whether the cause of the excess radiation exposure was due to human error or problems with the design of the CT scanners, we do not believe there is reason to be concerned about the safety of CT perfusion scans,” Jeffrey Shuren, MD, acting director of the FDA’s Center for Devices and Radiological Health, said during a press briefing.

In the meantime, the FDA reminds clinicians who perform CT scans to adhere to the following simple steps:

Assess whether patients who have undergone a CT perfusion scan have received access radiation.
Review radiation dosing protocols for all CT perfusion studies to ensure that the correct dosing is planned for each study.
Implement quality control procedures to ensure that dosing protocols are followed every time and that the planned amount of radiation is administered.
Check the CT scanner display panel before performing a study to make sure the amount of radiation to be delivered is at the appropriate level for the individual patient.
Adjust the dose of radiation if more than one study is performed on a single patient during one imaging session so that it is appropriate for each study.

Since the Los Angeles County Radiation Office reported the first two cases in October, officials have identified more patients at two other California hospitals — Glenndale Aventis Medical Center, also in Los Angeles County, and St. Joseph’s Medical Center in Burbank — and at undisclosed locations in Alabama.

Officials are concerned about the accuracy of treatment algorithms used to calculate the amount of radiation exposure for a given patient when clinicians administer multiple tests, according to Shuren, who said he would not be surprised to learn of similar occurrences in other states.

Shuren emphasized that it is too early to determine the exact cause of the over exposures, but noted that, to date, investigators have implicated scanners manufactured by General Electric and Toshiba.

“The FDA continues to work with state and local public health authorities, manufacturers of the CT units and professional organizations to identify other additional cases, as well as investigate the scope and cause of excess exposures,” said Simon Choi, PhD, network leader of radiologic products, also of the Center for Devices and Radiological Health.

Although it is too early to determine what additional actions the agency will pursue, Shuren said, the FDA plans to issue additional recommendations as more information becomes available. – by Nicole Blazek