Radionuklidit

Radionuklidit, or radionuclides, are atoms with unstable nuclei that decay by emitting ionizing radiation such as alpha, beta, or gamma rays. This decay transforms the nucleus into a more stable configuration and often creates a different element. Radionuklidit occur naturally and are also produced synthetically in laboratories, reactors, or accelerators.

Natural radionuklidit include primordial nuclides such as uranium-238, uranium-235, thorium-232, and potassium-40, as well as cosmogenic nuclides like carbon-14. Radon, a decay product of uranium and thorium, can contribute to indoor radiation exposure. Artificial radionuklidit are manufactured for medical, industrial, and research purposes, with examples including technetium-99m, iodine-131, cesium-137, cobalt-60, and plutonium-239. Isotopes vary widely in half-life, from fractions of a second to billions of years, influencing persistence and risk.

The activity of radionuklidit, measured in becquerels, indicates the number of decays per second; the absorbed dose is in grays, while the biological effect is expressed in sieverts. The relationship A = λN links activity to the number of undecayed nuclei, and the half-life t1/2 = ln(2)/λ describes the rate of decay.

Applications span medicine, industry, and science. Medical uses include diagnostic imaging with technetium-99m and PET isotopes, as well as targeted therapy with iodine-131 or lutetium-177. Industry employs radionuklidit for nondestructive testing and tracing, while science relies on them for dating, tracing processes, and materials analysis. Safety and regulation aim to limit exposure through shielding, containment, ventilation, and proper waste management. Environmental considerations include natural background radiation, radon, and remediation of contaminated sites, with international and national bodies providing guidelines to manage risks and applications.