Radiation poisoning cases lead FDA to issue new CT perfusion imaging guidelines

The FDA has issued a new set of preemptive recommendations after identifying at least 50 more stroke patients who were exposed to excessive radiation during CT perfusion of the brain.

An ongoing investigation has so far turned up 50 new cases of patients exposed to radiation doses nearly eight times higher than the accepted standard involving at least two CT scanner manufacturers and health facilities in several states. Patients connected with theses new cases have reported symptoms compatible with radiation poisoning, including skin burns and hair loss. As an interim measure while the investigation continues, the FDA issued the guidelines Dec. 7 aimed at practitioners and imaging facilities to help them prevent new cases.

The FDA issued the original alert Oct. 8 when it revealed that 206 patients who had undergone perfusion CT scans for imaging of stroke at Cedars-Sinai Medical Center in Los Angeles had been exposed to radiation doses of 3 Gy and 4 Gy. That exposure is far above the 0.5 Gy standard. Hospital officials revealed that modifications to the CT perfusion protocol involved in the accidents went undetected for 18 months.

The new guidelines apply to all types of CT perfusion imaging, not just the brain, and ask that providers:

• Identify patients who may have undergone perfusion CT scans with radiation doses in excess of recommended levels.
• Review dose protocols.

• Implement quality control procedures to ensure proper scanning doses apply to individual exams every time.

• Ensure radiation dose is appropriately adjusted if more than one study is performed on the same patient during the same imaging session.

The FDA has advised manufacturers to review customer training procedures and the information they share with healthcare facilities, as well as come up with new ways to identify these issues in a timely fashion.

Facilities should step up efforts to make sure perfusion CT exams are done safely, said Dr. Jeffrey Shuren, acting director of the FDA’s Center for Devices and Radiological Health.

“The FDA is making progress in the investigation of this problem,” Shuren said.

CT stakeholders, including members of the American College of Radiology and the Medical Imaging and Technology Alliance (MITA), a branch of the National Electrical Manufacturers Association, met with FDA officials Nov. 30 in Chicago during the 2009 RSNA meeting.

The FDA shared its recommendations with the group in advance of their release to the public and stressed the need to improve quality assurance in CT procedures to avoid new cases, said MITA’s director of industry programs Stephen Vastagh, who organized the stakeholders’ meeting.

“We want to cooperate in the FDA investigation and we want to do whatever we can to make sure that cases of radiation overexposure don’t happen anymore,” said MITA’s managing director Dave Fisher.