This article is dedicated to the history of the formation and development of radiation medicine, which is becoming increasingly widespread. Radiation treatment of various benign and malignant neoplasms with the help of contact use of ionizing radiation sources is called brachytherapy. To date, clinical brachytherapy has been divided into three areas: high-dose/high-power, low-dose/low-power, and electronic. Founded in the early 1980s, the Unit of Radionuclide Therapy at the Tsyb Medical Radiological Research Center (Obninsk), a branch of the National Medical Research Radiological Center of the Russian Ministry of Health, is the first and largest medical institution in Russia where radionuclides are used therapeutically. The authors conclude their review by identifying the main trends in the global nuclear medicine of the future.