The Food & Drug Administration said today that reports it investigated of overexposure to radiation during CT scans were likely due to human error, not malfunction.

The federal watchdog agency also issued recommendations for CT scan equipment makers aimed at reducing the risk of overexposure. The scanners could be made safer if their manufacturers provided more training to end users and the devices included radiation gauges and alarms indicating possible overexposure:

• A console notification to alert the operator of a high radiation dose
• Providing particular information and training on brain-perfusion protocols to all facilities that receive base CT equipment, whether or not the facilities purchase the related software enabling quantitative analysis of cerebral hemodynamics
• Clarification of parameters affecting dose, along with clear instructions on how to appropriately set those parameters
• 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

The FDA sent a letter to the Medical Imaging and Technology Alliance outlining the proposals. The agency said it is planning discussions over the changes with the industry.

MITA executive director Dave Fisher pledged in an email to MassDevice that his group will continue to work with the FDA and other stakeholders to reduce radiation levels.

“The recommendations in the FDA’s letter are issues we have been working on with the Agency over the last year and include an important component of MITA’s CT Dose Check Initiative, Fisher wrote. “While reported incidents have not been attributed to CT scanner malfunction, as part of our longstanding commitment to educating users and to developing technologies that reduce radiation levels, MITA looks forward to continuing our work with the FDA. In the end, the optimal solution will require action by all stakeholders including, manufacturers, users and regulators.”

The proposals are the result of the FDA’s investigation of excess radiation exposure for patients undergoing CT, or computed tomography, brain perfusion scans. The agency reported that since the investigation began, it discovered at least 385 patients who were exposed to unsafe levels from CT brain scans. Many of the victims were undergoing the test to confirm the presence of a stroke at five hospitals in California and another in Alabama.

Last month, 12 patients treated at Alabama’s Huntsville Hospital using CT scanners made by General Electric’s (NYSE:GE) healthcare unit filed a lawsuit against the company for receiving excess radiation from the devices. The plaintiffs said the scanners caused brain damage, memory loss, baldness and other symptoms, according to the suit.

The FDA today said that "improper use" of the scanner by its operator "likely" resulted in the overdoses. "[W]hen properly used, the CT scanners did not malfunction," according to an FDA press release. "While unnecessary radiation exposure should be avoided, a medically-needed CT scan has benefits that outweigh the radiation risks. Patients should follow their doctor’s recommendations for receiving CT scans."

In Dec. 2009, the FDA released interim guidance for all computerized axial tomographic perfusion imaging scans after a report in October that more than 200 patients were exposed to excess doses of radiation. As a result the agency released new standard operating procedures for all imaging facilities, radiologists and radiologic technologists. At the time, Centers for Devices and Radiological Health chief Dr. Jeffrey Shuren said officials had not at the time made a determination about whether the machines or human error were to blame.

Use of CT and MRI scans almost tripled in the 10 years between 1998 and 2007, according to a study by the Journal of the American Medical Assn., meaning many more patients were exposed to higher levels of radiation. Researchers from Johns Hopkins University in Baltimore studied data on emergency room visits from 1998 to 2007, looking for evidence that “excessive use of medical imaging increases healthcare costs and exposure to ionizing radiation (a potential carcinogen) without yielding significant benefits to all patients,” according to the JAMA report. They found that, while the use of the scans went from 6 percent of ER visits in 1998 to 17 percent in 2008, there was no corresponding increase in the diagnosis of life-threatening conditions or hospital admissions.

The scanners got a boost last week from a government-financed study. The research indicated that annual CT scans of current and former heavy smokers reduced their risk of death from lung cancer by 20 percent.