WASHINGTON -- The Food and Drug Administration will require new safety controls on medical imaging devices and encourage development of more precise radiation dosing standards in a bid to reduce unnecessary exposure of patients to diagnostic radiation.

The agency also will promote a personal medical imaging history card that will enable patients to keep track of the number of images, and the amount of radiation, they receive over time, according to a medical imaging safety initiative unveiled Tuesday.

The safety push comes five months after Cedars-Sinai Medical Center in Los Angeles discovered that it had accidentally exposed more than 260 patients to eight times the normal dose of radiation for CT brain scans over a period of 18 months. Three other facilities -- two in Los Angeles County and one in Huntsville, Ala. -- reported possible overdoses by equipment to at least 104 people.

Those mishaps provided a timely nudge to FDA planning already under way for better safety protocols and more comprehensive information-gathering to determine best-practice standards, said Jeffrey Shuren, director of the FDA's Center for Devices and Radiological Health.

"We're aware that the exposure of the American public to [diagnostic] radiation was increasing fairly dramatically over the past 20 years," Mr. Shuren said in an interview. "These tests can provide tremendous medical benefit. We're trying to optimize that benefit while lowering the risk."

The FDA will hold a public meeting March 30 and 31 to collect suggestions about the kinds of new safety features and training that should be required for CT and fluoroscopic devices, Mr. Shuren said.

A CT, or computed tomography scan, is a rapid series of X-rays that results in a series of highly detailed cross-sections of the body.

A fluoroscope uses an X-ray tube hooked to a monitor to produce a live-action shot of an organ, used most commonly in cardiac catheterization. The initiative also applies to nuclear medicine, commonly used in measuring cardiac stress.

Possible changes in imaging equipment include having it automatically calibrated to a recommended dose of radiation for a given procedure, so any dosage increase would require an action by the equipment operator. Equipment might also be designed to require identification of the operator as a way of tracking errors.

Mr. Shuren said regulators also are looking at software upgrades and other fixes to existing equipment. The FDA is encouraging development of a voluntary national database of information collected from imaging equipment nationwide to determine the optimal dosages for a given procedure, fine-tuned to variables such as age and body type. Such a database also would allow individual practitioners to measure their use of radiation against their peers, Mr. Shuren said.

That's Fascinating, where Mark Roth spotlights the odd and the interesting in everyday life, is featured exclusively in the Opinion section on PG+, a members-only web site from the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.