Positron emission tomography (PET) is an important tool for early disease detection, understanding of molecular aspects of brain function, and evaluating medical treatment. This course reviews the fundamental concepts of PET imaging and explores its applications in brain research and drug development. Taught by a multidisciplinary team — chemists, physicists, imaging scientists, and clinician scientists — the course provides insights from experts actively engaged in various aspects of PET brain imaging. Their research spans from furthering our understanding of healthy brain function, to studying brain disorders, such as schizophrenia, mood disorders, addictions, neurodegenerative diseases, and movement disorders. This course will explore specific topics in the context of addressing fundamental research questions. Key areas of focus include: (1) the chemistry of labelling compounds with short-lived positron-emitting radionuclides; (2) the design of PET radiopharmaceuticals and their influence on PET data interpretation, including labelling position, metabolism, the distinction between drugs and radioligands; (3) cyclotron principles; (4) PET physics and instrumentation; (5) PET data analysis and quantification; and (6) the applications of PET in brain research and drug development.