2026-04-292026-04-292026https://repositorio.ifal.edu.br/handle/123456789/3024This work analyzes the applications of radioactivity in Nuclear Medicine and Radiotherapy, addressing its historical evolution, physical foundations, diagnostic and therapeutic methods, as well as the principles of radiation protection.The study, qualitative in approach, exploratory in nature, and bibliographic in character, was based on scientific sources obtained from articles and databases such as Google Scholar, SciELO, and CAPES journals. It examines essential concepts of radioactivity, such as types of radiation and decay mechanisms, and discusses the technological development that enabled the emergence of functional imaging techniques. The research also describes the advancement of therapeutic methods, with emphasis on external beam radiotherapy, brachytherapy, and the use of specific isotopes such as iodine-131, highlighting their effectiveness in the treatment of neoplasms and thyroid diseases. The results show that ionizing radiation has become an indispensable tool for early diagnosis and clinical monitoring, contributing to greater therapeutic precision and increased patient survival. The study concludes that, despite the benefits, the use of radiation requires strict adherence to radiological protection standards due to the associated biological risks and highlights the need for investments in infrastructure and professional training to expand access to advanced technologies in Brazil.ptRadiação ionizanteTerapia NuclearRadioterapiaDiagnóstico por imagem.Trabalho de Conclusão de CursoCIENCIAS EXATAS E DA TERRA::QUIMICA