[Radioactive Isotope] Radioisotopes are atoms with an unstable nucleus, which try to reach a more stable state by emitting radiation. Through one or more steps down its decay chain a more stable number of protons and neutrons is reached. Approximately 3,800 natural and artificial (fission, generator) radioisotopes exist. Radioisotopes are commonly used in science, industry, and nuclear medicine.

See also Isotope, Decay and Decay Chain.

(RSNA) The Radiological Society of North America, established in 1915, has the mission to promote and develop the highest standards of radiology and related sciences through education and research.

(RIS) Radiology department computer software system to manage patient details, records, images, tracking and scheduling, etc.

Radionuclides are naturally occurring or artificially produced atoms with unstable nuclei. Therefore radionuclides undergo a radioactive decay, and emit gamma ray(s) and/or subatomic particles.
Radionuclides are used as agents in nuclear medicine and to destroy tumors in cancer therapy.

See Isotope and Radioactive Decay.

Radiopaque materials are not penetrable by radiation or impede x-rays. Radiopaque substances appear white on radiographic images.

See also Contrast Agents.