FDA Investigates CT Scan Radiation Overdoses
Agency concludes that scanners did not malfunction; improper use the likely cause of excess radiation.
The U.S. Food and Drug Administration (FDA) has been investigating reports that patients undergoing computed tomography (CT) brain perfusion scans were accidently exposed to excess radiation. The FDA said it is aware of at least 385 patients who received excessive radiation from CT brain perfusion scans, many undergoing the test to confirm the presence of a stroke, performed at five hospitals in California and one in Alabama.
Begun in 2009, the FDA's investigation included information from the states and facilities where radiation overdoses occurred from 2008 to Oct. 26, 2010. The agency also inspected CT scanner equipment manufacturers.
On Nov. 9, the FDA reported that the CT scanners did not malfunction when properly used. The FDA concluded that improper use of the scanners was the likely cause of the reported overdoses.
On Nov. 8, Jeffrey Shuren, MD, director of FDA's Center for Devices and Radiological Health, sent a letter to the Medical Imaging and Technology Alliance, the major professional industry organization for manufacturers of CT scanners and other radiological imaging devices, reporting on the results of the investigation. The letter discussed possible CT equipment enhancements that could improve patient safety. According to Dr. Shuren, the recommended changes "pertain for the most part to re-organizing or developing additional equipment-operation information that users could readily access, understand and apply to reduce the possibility of inadvertent application of unnecessary amounts of radiation."
Those changes include:
- a console notification to alert the operator of a high radiation dose;
- providing specific information and training on brain-perfusion protocols to all facilities receiving base CT equipment, whether or not the facilities purchase the related software enabling quantitative analysis of cerebral hemodynamics;
- clarification of parameters affecting dose, along with clear instructions on how to appropriately set those parameters; and
- organization of all dose-related information into one section of each user manual, in a dedicated dose manual, or indexed comprehensively in a reference covering all manuals.
The FDA said it will hold follow-up discussions with manufacturers on the changes.
The FDA also noted, "While unnecessary radiation exposure should be avoided, a medically-needed CT scan has benefits that outweigh the radiation risks. Patients should follow their doctor's recommendations for receiving CT scans."