The FDA cleared GE Healthcare and Toshiba America Medical Systems of any blame for the overexposure of hundreds of patients to CT-induced radiation resulting from brain perfusion scans.

The FDA's announcement followed an investigation into whether GE and Toshiba CT scanners provided appropriate protocols for safe usage and whether either manufacturer had modified any of the six hospitals' protocols to cause the overexposure. The FDA found no violations of laws or regulations by either company.

The FDA launched an investigation in October of 2009 into the overexposure of 206 patients overexposed to CT radiation at Cedars-Sinai Medical Center in Los Angeles. The agency now reports that the investigation expanded to cover six hospitals and 385 patients. According to the FDA, both GE and Toshiba's protocols provided "reasonable and appropriate image quality and dose."

Room for improvement
Accompanying the exoneration, the FDA sent and published a letter to the Medical Imaging Technology Alliance (MITA) outlining steps that manufacturers could take to improve safety and lower the risk of future patients' overexposure to radiation, including:

• Provision of information and training on brain perfusion CT scans to all facilities purchasing their scanners, with the aim of informing all institutions of the safe and effective parameters required for different scans;
• Instruction on the proper use of automated exposure control on CT scans and when and how hospitals and patients would benefit from manual parameter-setting;
• An alert system that automatically informs CT operators when parameters are set at levels that would cause injury to the patient;
• Creation of an organized manual dedicated to CT dose-related information; and
• Specific manufacturer recommendations for clinical scanning parameters and settings for all scanning sequences as well as estimates and explanations of dose values for each scan.

The FDA expressed the intention that the letter and recommendations trigger a dialogue in which the agency and all manufacturers and stakeholders can discuss improvements to CT safety and quality.

The FDA's letter to MITA can be found here.