This lecture discusses the use of radioactive tracers in medical imaging, focusing on the example of thallium-201 for myocardial scintigraphy. It covers the nuclear reactions involved in producing thallium-201, the calculation of initial nuclei and corresponding mass, toxicity assessment, and the concept of half-life. Additionally, it explores the development of a technique for dating wines using cesium-137, a product of nuclear fission. The lecture explains the principles of fission reactions, isotopes, and the detection of cesium-137 in wines to determine their vintage. It also delves into the decay process, energy release, and the application of radioactive decay in authenticating wines.