radioizotopy

Radioisotopy, also called radioisotope science, is the study of radioactive isotopes and their behavior in matter. It covers both fundamental aspects of radioactivity and practical applications that rely on the properties of isotopes to trace, image, or treat biological and physical systems.

Radioisotopes are atoms with unstable nuclei that decay to more stable forms, emitting charged particles or electromagnetic radiation. Decay modes include alpha, beta, and gamma decay. Each isotope has a characteristic half-life, from fractions of a second to millions of years. They may occur naturally or be produced artificially in reactors, cyclotrons, or generators.

In medicine, radiopharmaceuticals enable diagnostic imaging and targeted therapy. Positron emitters such as fluorine-18 and other PET isotopes are used with tomography, while gamma emitters such as technetium-99m support SPECT imaging. Therapeutic isotopes, including iodine-131, lutetium-177, and actinium-225, deliver dose to specific tissues.

Outside medicine, radioisotopes serve as tracers in biology, chemistry, and environmental studies, as well as in industry for non-destructive testing and process tracing. They are also used in geological dating, notably carbon-14 and uranium-lead systems, and in archaeology and hydrology.

Safety and regulation are central to radioisotopy. Handling requires radiation protection, proper shielding, monitoring, waste management, and compliance with national and international rules.

The field emerged with the discovery of radioactivity by Henri Becquerel in 1896 and the subsequent work of Marie and Pierre Curie; the concept of isotopes was developed by Frederick Soddy.