Positron emission tomography (PET) and more recently PET/computed tomography (CT) has been utilized as a measure of functional imaging for many decades. The manufacture of PET radiotracers for imaging molecular processes in the human brain begins with the production of the PET radioisotope using a cyclotron. A nuclear reaction takes place in the target between the particle and the atom of the target material that gives rise to the PET radioisotope. The radioisotope is then sent to the radiopharmacy where it is used in the preparation of a radiopharmaceutical. Different patient protocols for PET imaging with 18F fluorodeoxyglucose (18F-FDG) are present for oncological and cardiac indications. PET regional cerebral blood flow (rCBF) imaging with 15O-water can be quantified using a mathematical model using a diffusible tracer technique method. Software has been developed to assess imaging more quantitatively with comparison to normal subjects.