FDA worried about radiation risk from whole-body CT for routine screening

Last Updated: 2001-05-17 17:47:06 EDT (Reuters Health) - Regulators at the Food and Drug Administration are concerned that the growing popularity of whole-body computed tomography for health screening could be exposing the public to risky levels of radiation.

Thanks to recent advances in CT, the machines can now cheaply and quickly scan patients' whole bodies instead of just small areas of tissue. The changes have helped spawn a new nationwide industry of unregulated "boutique clinics" where patients pay $300 to $500 of their own money to get CT scans--not for diagnosis, but for regular health screening, officials told an FDA advisory panel Thursday.

The agency is worried that whole-body CT, which requires a higher dose of radiation than targeted imaging, might expose patients to unhealthy doses of radiation. While the FDA evaluates the safety and effectiveness of CT scanners and other medical devices for regular use, it has no power to regulate how those machines are used once they reach physicians' offices.

"We don't have dose limits on CT. How the operator uses it is totally out of our control," Dr. Thomas B. Shope, a special assistant at FDA's Center for Devices and Radiological Health, said in an interview with Reuters Health.

As more and more people visit clinics to be screened for lung cancer, coronary artery disease, and other ailments, they could be absorbing more radiation more often than the FDA intended, panelists warned.

"It's an open free-for-all in many communities," said Dr. John F. Cardella, a member of the advisory panel and the chief of the radiology department at the State University of New York Upstate Medical University in Syracuse. "There is a perception by the public that CT scanning is a benign thing," he said.

"We don't really have a feel for just how many boutique clinics are operating. It's something we need to have an awareness of," Dr. Shope said.

He told the panel that the average whole-body CT scan delivers 0.2 to 2.0 rads of radiation, depending on the size of the patient's body. Studies of Japanese survivors of the US atomic attacks on Hiroshima and Nagasaki in World War II linked an increased risk of cancer to lifetime cumulative exposures of 5 to 20 rads.

"At 2 rads per exam, we're not far" from potentially dangerous radiation doses, Dr. Shope said.

Dr. Shope said there is growing interest within the FDA and the CT industry in technology that allows machines to automatically adjust the radiation dose depending on how much radiation the body absorbs during a scan. Such advances might help physicians minimize the potential danger of repeat CT scans in an uncontrolled environment.