It's 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. A public meeting to discuss the requirements is scheduled for late-March.
Regulators are also developing best-practice measures that hospitals and imaging centers will have to meet to retain their scanning accreditation.
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.
Tuesday's announcement comes five months after FDA began looking into reports of problems with CT scanning at Cedars-Sinai Medical Center in Los Angeles.
More than 250 patients were exposed to excess radiation, with many reporting losing hair and skin redness. Since then the FDA has begun investigating similar problems at two other California hospitals.
CT scans became popular because they offer a quick, relatively cheap and painless 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 less intensive scans. One CT chest scan carries as much radiation as nearly 400 chest X-rays, according to government officials.
The FDA's effort will extend to other high-dose types of radiation procedures, including 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.
