FDA readies effort to prevent CT radiation overdoses

November 9, 2010
Greg Freiherr

Vendors have tried to walk a thin line between providing equipment and prescribing its use. Automated protocols and image processing have been enhanced to make imaging products easier to use and the images they deliver more consistent from one user to another. But they have stopped short of mandating technologies that otherwise impact the practice of medicine. Now the FDA wants equipment makers to expand their role.

Vendors have tried to walk a thin line between providing equipment and prescribing its use. Automated protocols and image processing have been enhanced to make imaging products easier to use and the images they deliver more consistent from one user to another. But they have stopped short of mandating technologies that otherwise impact the practice of medicine. Now the FDA wants equipment makers to expand their role.

In a letter sent this week to the Medical Imaging and Technology Alliance (MITA), which represents manufacturers of radiological devices, the FDA said it will ask equipment makers to develop technology and training programs to reduce the chance of patients being overdosed during CT scans.

A chief request will be for manufacturers to build a warning system into CT consoles to alert operators before a high radiation dose is given a patient. The FDA also wants vendors to educate and better train CT users to perform brain-perfusion protocols; clarify equipment operating parameters that affect dose, as well as provide clear instructions on how to appropriately set those parameters; and organize dose-related information so that it can be more easily found in user manuals accompanying CT scanners.

Spurring the FDA to look specifically at CT brain perfusion was the discovery last year that patients had been overdosed with radiation while undergoing this type of scan at hospitals in California and Alabama. As 2009 drew to a close, the FDA issued recommendations aimed at reducing the chance of radiation overdose from CT.

The agency has since found at least 385 patients have received excessive radiation from CT brain perfusion scans, many during tests performed at six hospitals in these states. Its investigation included information documenting radiation overdoses beginning in 2008 and happening as late as Oct. 26, 2010. As part of its probe, the agency also inspected CT scanner equipment manufacturers.

Investigators found that CT scanners, if properly used, do not overdose patients. But the chance of radiation overdose can be reduced with equipment enhancements.

“Patients should not have to worry that a device designed to diagnose an illness exposes them to unnecessary risks,” said Dr. Jeffrey Shuren, director of FDA’s Center for Devices and Radiological Health. The agency plans to hold follow-up discussions with manufacturers on changes in equipment and training that will make CT scans safer, specifically CT brain perfusion scans. These discussions will be part of the agency's Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging, which covers x-ray fluoroscopy as well as CT.