U.S. health officials want manufacturers of CT machines and certain other medical imaging devices to incorporate new safeguards to help reduce patient exposure to radiation.

The U.S. Food and Drug Administration said on Tuesday it planned to issue requirements for manufacturers to use when designing their equipment and would hold a public meeting on the matter March 30-31.

The agency says possible examples could include changes so that imaging devices display equipment settings and radiation dose, or sound an alert if the dose is too high.

New requirements would affect imaging machine manufacturers such as General Electric, Toshiba, Hitachi Ltd, and Siemens as well as smaller companies such as Varian Medical Systems, Inc. and Digirad Corp.

While medical imaging scans aim to help doctors diagnose a problem, they can increase patients' risk for cancer, the agency said. Accidental exposure to high doses of radiation can cause skin burns, cataracts and other injuries.

The FDA said in December it was investigating several cases of patients who were exposed to up to eight times the normal level of radiation from brain scans performed with equipment from GE and Toshiba.

"While there is some disagreement over the extent of the cancer risk associated with exposure to radiation from medical imaging, there is broad agreement that steps can and should be taken to reduce unnecessary radiation exposure," the FDA said in a statement on Tuesday.

The FDA said it was most concerned with the effects of computerized tomography (CT), nuclear medicine studies and continuous X-ray fluoroscopy—"the greatest contributors to total radiation exposure within the U.S. population"—than other procedures using lower radiation doses such as standard X-rays and mammography.

Patients also need to be aware of their exposure to radiation and should keep track of it, the FDA said.

Radiation dangers from such tests have been known for decades and outside data in the FDA's own report showed roughly 29,000 future U.S. cancer cases may be linked to CT scans performed in 2007, consumer advocate Sidney Wolfe said.

"The belated and inappropriately tentative FDA statements are not adequate for this serious threat to the public health," said Wolfe, head of Public Citizen's Health Research Group.

FDA's device center has been under fire for a variety reasons, including its product reviews and staff scientist complaints. FDA Commissioner Margaret Hamburg has vowed to improve the unit and in January tapped a new center director.

Frank Pallone, head of the House of Representatives Energy and Commerce subcommittee that postponed a planned Wednesday hearing on the issue due to heavy snow forecast for Washington DC, called the FDA's plan "a good first step."

Medical device-makers have said they advocate appropriate use of technology, including imaging tests.

A representative for the Advanced Medical Technology Association, an industry group, said advanced medical imaging and nuclear medicine is more effective at diagnosing diseases, adding that it was reviewing the FDA's action ahead of the March public meeting.

Another industry group, the Medical Imaging & Technology Alliance, had no immediate comment.

(Reporting by Susan Heavey; Editing by Maureen Bavdek and Tim Dobbyn, )