WASHINGTON -- A system for producing medically important technetium-99m isotopes within the U.S. without relying on highly enriched uranium as source material won FDA approval Thursday, the agency announced.

Until now, Tc-99m isotopes -- widely used in radiology as an imaging tracer -- were available only from foreign suppliers. Since 2012, U.S. policy has been to eliminate reliance on highly enriched uranium as a source for medical radioisotopes and to develop domestic supplies of Tc-99m and its parent element, molybdenum-99, the FDA noted.

"Every day, tens of thousands of people in the U.S. undergo a nuclear medical imaging procedure that depends on Tc-99m," said Janet Woodcock, MD, director of the FDA's Center for Drug Evaluation and Research, in a statement. "This radioisotope is vital to disease detection, yet healthcare professionals have faced challenges with adequate supply due to a complex supply chain that sometimes resulted in shortages. Today's approval has been the result of years of coordination across the FDA and with U.S. government organizations and marks the first domestic supply of Mo-99 – the source of Tc-99m – in 30 years, which will help to ensure more reliable, clean, and secure access to this important imaging agent used in nuclear medicine."

As part of Thursday's action, the Nuclear Regulatory Commission (NRC) is issuing guidance for nuclear pharmacies on the license amendments they must obtain in order to buy and use the RadioGenix System. The NRC is the government agency responsible for regulating production and possession of radioactive materials.

The system, developed by Northstar Medical Radioisotopes of Beloit, Wis., uses a three-step process to generate radioactive Mo-99 from naturally occurring molybdenum ores.