US Agency Working to Help Prevent Radiation Overdoses during CT Scans

A US federal agency has been investigating reports that patients undergoing computed tomography (CT) brain perfusion scans were accidentally exposed to excess radiation. The investigators found that when appropriately used, the CT scanners did not malfunction. Instead, it is likely that the improper use of the scanners resulted in these overdoses.

However, the US Food and Drug Administration (Silver Spring, MD, USA) has identified a series of steps to enhance the safety of these procedures. These steps could reduce the likelihood of radiation overexposure in the event of improper use of the CT scanners.

The FDA has sent a letter to the Medical Imaging and Technology Alliance (Arlington, VA, USA), the major professional industry organization for manufacturers of CT scanners and other radiologic imaging devices, reporting on the findings of the investigation and discussing possible CT equipment enhancements that could improve patient safety. The agency will hold follow up discussions with manufacturers on the changes.

Those changes include a console notification to alert the operator of a high radiation dose; the provision of particular 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, combined with distinct instructions on how to correctly set those parameters; and lastly, organization of all dose-related information into one section of each user manual, in a dedicated dose manual, or indexed comprehensively in a concordance covering all manuals.

CT brain perfusion scans produce cross-sectional images of the head that assess blood flow in the brain. In an update released November 10, 2010, the FDA discussed findings of a probe into radiation overdoses in patients who received CT brain perfusion scans in hospitals located in California and Alabama.

Begun in 2009, the FDA's investigation included information from the states and facilities where radiation overdoses occurred from 2008 to October 26, 2010. The agency also inspected CT scanner equipment manufacturers. The probe indicated that CT scanners, when correctly used, did not result in overdoses. However, the study found potential enhancements to CT equipment that could reduce the probability of radiation overexposure if improper use occurs--a goal of the agency's Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging.

Since the investigation began, the FDA is aware of at least 385 patients who received excessive radiation from CT brain perfusion scans, many undergoing the test to validate the presence of a stroke, performed at five hospitals in California and one in Alabama.

Related Links:
Food and Drug Administration
Medical Imaging and Technology Alliance