February 9, 2010
Federal regulators will require manufacturers of high-grade medical imaging machines to include safety controls that prevent patients from receiving excessive radiation doses.
The proposal is part of an effort to areduce reports of acute injuries as well as reduce total lifetime exposure to radiation, which has nearly doubled since 1980.
The Food and Drug Administration (FDA) push will focus on high-tech machines such as CT scanners, which allow doctors to make lifesaving diagnoses, but also expose patients to high doses of radiation which can potentially cause cancer years later.
FDA officials told manufacturers to install safeguards on their machines that automatically notify operators if they are using a higher-than-recommended dose. Regulators are also developing best-practice measures that hospitals and imaging centers will have to meet to retain their scanning accreditation. A public meeting to discuss the proposals with physicians and manufacturers is scheduled for late March 2010.
The average American's total radiation exposure has nearly doubled in the last three decades, largely due to CT scans and other next-generation imaging tests, according to recent studies. Medical radiation now accounts for more than half of the population's total radiation exposure; it used to be just one-sixth. The majority of the rest of the radiation exposure comes from the natural environment around us called background radiation.
FDA's initiative comes five months after regulators began looking into reports of acute overdoses from CT scanning at Cedars-Sinai Medical Center in Los Angeles. More than 250 patients there were exposed to excessive radiation, with many reporting losing hair and skin redness. Since then the FDA has launched investigations into similar problems at two other California hospitals.
There is some disagreement over the cancer risk associated with medical imaging, though virtually all medical societies recommend minimizing radiation exposure. An analysis published last year in the Archives of Internal Medicine estimated 29,000 future cancers could be related to CT scans performed in 2007.
Dr. Sidney Wolfe of the consumer advocacy group Public Citizen questioned why the FDA's actions were so long in coming.
"Why is the agency just articulating them and considering action on them now?" asked Wolfe, a frequent critic of the FDA. "The papers cited by the agency ... go back as far as several years and the authors of these papers certainly described problems begging for definitive action."
Wolfe, who directs the group's health division, also criticized the FDA's "inappropriately tentative" approach to regulation by offering proposals to industry, rather than issuing ultimatums.
CT scans became popular because they offer a quick, relatively cheap way to get three-dimensional pictures that give an almost surgical view of the body. Doctors use them to evaluate trauma, belly pain, seizures, chronic headaches and other ailments. However, they also carry a higher risk than older scans. One CT chest scan carries as much radiation as nearly four hundred chest X-rays, according to government officials.
The FDA's effort will also try to curb excessive radiation exposure from two other types of imaging: nuclear medicine and fluoroscopy. Nuclear medicine involves injecting nuclear particles into the body to diagnose problems with organs, such as the heart and lungs. Fluoroscopy uses a continuous X-ray beam to view body parts in real time.
The industry's trade association said it welcomed the government initiative and would cooperate "to ensure patients get the right scan at the right time."
General Electric, Siemens Aktiengesellshaft and Toshiba Corporation are among the manufacturers represented by the Medical Imaging and Technology Alliance