Hot rolling: Heating metal above its recrystalization temperature before rolling it to form sheets.

Isomeric transition: Radioactive decay process in which the nucleus of a metastable isotope has an elevated energy state and releases this energy by emitting a gamma ray.

Large-scale producer: Producers of Mo-99 who supply more than 1000 6-day curies of Mo-99 per week to the market on a routine basis.

Low enriched uranium: Uranium enriched to concentrations less than 20 percent by weight of U-235.

Medical isotopes: Class of radioactive isotopes (radioisotopes) that have unstable nuclei and emit radiation. This radiation is used for medical imaging and treatment.

Neutron capture: Process involving the capture of neutrons by an atomic nucleus to form a heavier nucleus.

Neutron flux: Measure of the intensity of neutron radiation, defined as the number of neutrons crossing a unit area of a square centimeter in one second (neutrons/cm2-s).

New drug application (NDA): A written application to the Food and Drug Administration seeking approval to sell a pharmaceutical in the United States.

Perfusion: Delivery of arterial blood to biological tissue.

Perfusion reserve: Capacity of flow through a blood vessel system in an organ under a stress or stimulus.

Regional producers: Producers who supply Mo-99 for indigenous or regional use in less than large-scale quantities.

Significant quantity: Approximate quantity of material from which the possibility of manufacturing a nuclear explosive device (i.e., a device that can achieve a prompt critical mass) cannot be excluded.

Special nuclear materials: Fissile material or material that is capable of sustaining a chain reaction of nuclear fission. It includes plutonium and uranium enriched in the isotopes U-233 or U-235.

Stenosis: Abnormal narrowing of a blood vessel.

Supplemental new drug application (sNDA): Additional written documentation submitted for approval by the FDA when a producer makes major changes to the process or raw materials it uses to make a pharmaceutical.

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