FDA Updates Guidance on Making CT Brain Scans Safer
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November 9, 2010 — To protect patients undergoing computed tomography (CT) brain perfusion scans from excessive radiation, the US Food and Drug Administration (FDA) today recommended that imaging facilities and professionals emphasize better training and precautions as simple as double-checking the display panel of the CT machine before hitting the button.
The recommendations come in the wake of a year-long investigation of hundreds of patients who were accidentally exposed to excessive CT radiation, as well as an investigation of GE Healthcare and Toshiba America Medical Systems, the manufacturers of the scanners involved. In December 2009, the FDA issued interim guidelines to address these safety concerns.
The FDA now concludes that the radiation overdoses probably resulted from improper use of the scanners, as opposed to faulty equipment design, although the agency suggested ways for all manufacturers to make the technology more foolproof.
Excessive radiation from CT brain perfusion scans to diagnose and treat stroke can result in hair loss or skin redness but also may not produce any obvious signs. If the problem is undetected, patients may undergo excessive radiation exposure over time that increases the risk for cancer.
Today's FDA announcement tries to avoid dampening faith in the procedure. "A medically-needed CT scan that does not expose the patient to unnecessary radiation has benefits that far outweigh the radiation risks," the agency states.
Misuse of Automatic Exposure Control Can Lead to Overexposure
FDA recommendations on how imaging facilities and professionals can avoid radiation overdoses with CT brain perfusion scans stress the need for painstaking thoughtfulness.
For example, if more than 1 study is planned for a scanning session, imaging professionals should adjust the dose so that it is appropriate for each study — the opposite of a set-it-and-forget mindset. Likewise, they should check the display panel of the machine before performing each scan to ensure that the amount of radiation shown is the right one for the patient. After the session, they should assess whether the patient received too high a dose.
The FDA also said that CT operators should be trained on the specific scanner and imaging protocol they are using, with particular attention paid to dose-saving features such as automatic exposure control. Used improperly, automatic exposure control can lead to patients receiving too much radiation, according to the FDA.
CT Machines Should Warn Operators Before Harmful Radiation Exposure
Yesterday, the FDA issued a letter to the Medical Imaging & Technology Alliance, an association of radiological imaging-device manufacturers, listing a number of steps these companies could take to minimize user error.
The agency said, for example, that any facility buying basic CT equipment should receive information and training on brain-perfusion protocols, regardless of whether they buy the software for such scans. Another recommended safeguard is tweaking the software to warn equipment operators through a "pop-up notification" that the planned radiation dose could possibly harm the patient.
CT Is 1 of 3 Imaging Modalities Targeted by FDA
The current push for safer CT scanning began last year, when the FDA investigated the cases of more than 200 patients who had received 8 times the radiation intended when undergoing CT brain perfusion scans at Cedars-Sinai Medical Center in Los Angeles, California. The agency said today that as of October 26 of this year, it knew of 385 patients from 6 hospitals who were exposed to excessive radiation during such scans.
In February this year, the FDA launched a campaign called the Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging. The campaign focuses on CT, nuclear medicine studies, and fluoroscopy — 3 modalities that account for 89% of the annual radiation exposure that patients get from medical imaging, according to the agency.
Finally, in April, the FDA tightened the approval process for radiotherapy devices, notifying manufacturers they can no longer count on winning approval for their products through the speedy, streamlined review processes previously available to them.
More information about today's announcement is available on the FDA Web site.
To report adverse events related to CT brain perfusion scans, contact MedWatch, the FDA's safety information and adverse event reporting program, by telephone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at http://www.fda.gov/medwatch, or by mail to MedWatch, FDA, 5600 Fishers Lane, Rockville, Maryland 20852-9787.