The Food and Drug Administration is working with doctors and medical manufacturers to reduce unnecessary radiation exposure from medical scans, a problem that has been growing for decades.

The agency says it will require manufacturers of CT scanners and other imaging machines to include safety controls that prevent patients from receiving excessive radiation doses.

The proposal is part of a multipronged effort to rein in radiation-based medical scanning, which has mushroomed in recent decades.

The average American's total radiation exposure has nearly doubled since 1980, largely because of CT scans, according to recent studies. Medical radiation now accounts for more than half of the population's total exposure; it used to be just one-sixth.