radioisotopesthe

Radioisotopes are radioactive isotopes of chemical elements. Unlike their stable counterparts, they contain an unstable combination of neutrons and protons that leads to spontaneous radioactive decay, releasing alpha, beta, and/or gamma radiation. Radioisotopes occur naturally from cosmic-ray interactions or radioactive decay in the Earth's crust, and they can also be produced artificially in nuclear reactors or particle accelerators. Each radioisotope has a characteristic half-life, the time required for half of a sample to decay, which ranges from fractions of a second to millions of years. The activity of a sample is measured in becquerels or curies and depends on the isotope number, quantity, and irradiation history.

Production and separation: Natural radioisotopes arise from primordial decay chains or cosmic ray interactions. Artificial production typically involves neutron activation in reactors (creating isotopes such as I-131 or Xe-133) or irradiation in accelerators to create positron emitters or therapeutic isotopes (Lu-177, Ga-68). Chemical separation and purification yield usable isotopes for medical, industrial, or research purposes.

Applications: In medicine, radioisotopes enable diagnostic imaging (technetium-99m, I-123, gallium-67) and targeted radiotherapy (I-131, Lu-177). In industry, sealed sources such as Cs-137 and Co-60 provide radiography and sterilization. In science, radiolabeling and radiometric dating (carbon-14) are common techniques.

Safety and regulation: Handling radioisotopes requires shielding, monitoring, waste management, and adherence to radiation safety standards established by national authorities and international bodies. Proper containment, training, and licensing minimize exposure to workers and the environment.