What is the first related word that comes to mind in association with the word "nuclear"? Some will call the word "energy," others "bomb. It's hard to believe today, but the first attempts at treatment with radionuclides were made more than a century ago, in 1901, when two French physicists proposed trying to treat skin tuberculosis with radioactive radium (pardon the tautology). Two years later, one of the inventors of the telephone, A. Bell, suggested that radium could also be used to treat cancer. Another 10 years later, in 1913, the Hungarian scientist and chemist D. Hevesy proposed the method of labeled atoms as a diagnostic tool. For this, incidentally, three decades later, Hevesy received the Nobel Prize in Chemistry. The first radionuclide-based medicine was prepared in 1941 by the American scientist S. Hertz. Ten years later, the first scanner for radionuclide diagnostics appeared, created by a team led by B. Kassen. Two years after that, a prototype positron emission tomography (PET) scanner is created in Gordon Brownell's laboratory. In 1959, Pennsylvania began testing the prototype of a single-photon emission machine for computed tomography, and in 1961 came the PET tomograph, the ancestor of most modern computer tomographs. One year earlier, the work of Rosalyn Yalow and Solomon Burson appeared, describing the method of radioimmune analysis, which gave rise to the whole area of in vitro, that is, out of body, in vitro diagnostics. The first attempt to treat a tumor with a directed beam of alpha particles was made in 1952 in the United States. In the beginning, only radium was used, but after a few decades, scientists began to produce various radioactive isotopes specifically for biology and medicine. A cyclotron was used for production, the first of which was created in 1929 by E. Lawrence. Iodine, phosphorus, carbon, thallium, technetium, fluorine, yttrium, samarium, strontium, and other isotopes are currently used in medicine. Statistically, more than half of all isotopes produced, 51%, are used in medicine.