This program, the first in a two-part series on nuclear medicine, includes a brief history of Positron-Emission Tomography in medical imaging and an explanation of radiotracers and the means of their detection in the imaging process. It discusses preparation of the radiotracers and offers overviews of attenuation correction, 2D and 3D reconstruction, and "Time of Flight" technique. The program describes the applications of PET in oncology, neuroimaging, cognitive neuroscience, and other areas of diagnosis and research. The program also covers use of 18F-FDG and provides an overview of the FDG PET/CT scanning procedure, as well as a general discussion on image scales and examples of tumor imaging. It concludes with a brief look at the perceived future of PET imaging technology.