The U.S. Food and Drug Administration has determined that the improper use of CT scan machines by hospital technicians led to the radiation overdoses suffered by 269 patients at Cedars-Sinai Medical Center between February 2008 and August 2009, as well as radiation overdoses at other hospitals in California and Alabama. The patients at Cedars-Sinai received eight-times the normal dosage of radiation during CT brain perfusion scans, a procedure used to diagnose strokes.

The FDA launched an investigation last year into the CT scan machines and the procedures hospitals follow when the overdoses were discovered at Cedars-Sinai. The investigation determined that radiation overdoses also occurred at other hospitals in the Los Angeles area, including Glendale Adventist Medical Center and Providence St. Joseph Medical Center in Burbank. Additional cases were discovered at hospitals in other parts of California, and in other states. The FDA determined that 385 patients who received CT brain perfusion scans at five hospitals in California, and one in Alabama, received radiation overdoses.

The agency’s investigation found that when properly used, the CT scanners did not malfunction. Instead, it is likely that the improper use of the scanners resulted in the overdoses. The FDA is recommending a series of steps to enhance the safety of CT scans that are designed to 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, the major professional industry organization for manufacturers of CT scanners and other radiological imaging devices outlining safety changes.

The changes include manufacturing CT scan machines with a console notification device to alert the operator of a high radiation dose; providing information and training on brain-perfusion protocols to all facilities that use CT equipment; 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 machine’s user manual.

“Improving patient safety is part of our public health mission,” said Dr. Jeffrey Shuren, director of FDA’s Center for Devices and Radiological Health. “Patients should not have to worry that a device designed to diagnose an illness exposes them to unnecessary risks.”

Cedars-Sinai Medical Center was cited for deficiencies in protocol by the California Department of Public Health for the radiation overdoses, but the department did not levy any fines. The hospital put in place measures to correct the problem, which met the state’s requirements. A written statement from the hospital said the corrective actions include “double checks to our process whenever a protocol is changed”, and a retraining of staff that operates the machines. The radiation overdoses at Cedars-Sinai also prompted a new law requiring the dosage of radiation to be indicated on the imaging film the CT scan machines produce, as well in the patient’s permanent medical record. The bill also requires hospitals to report any over-radiation to patients, the treating physician and the California Department of Public Health. In addition, hospitals are required to verify the calibration on CT machines on an annual basis, in compliance with federal law.

The FDA’s investigation found that while unnecessary radiation exposure should be avoided, a medically-needed CT scan has benefits that outweigh the radiation risks. The agency recommended that patients follow their doctor’s recommendations for receiving CT scans.

Approximately 90 of the patients who received radiation overdoses at Cedars-Sinai Medical are now suing the hospital.