Positron Emission Tomography, or PET, is a medical imaging technique that helps visualize metabolic processes in the body. It uses a small amount of radioactive material, which emits positrons, to create detailed images of organs and tissues. This technique is particularly useful in detecting cancer, monitoring treatment responses, and studying brain functions. During a PET scan, a patient is injected with a radiotracer that accumulates in areas of high metabolic activity. The emitted positrons collide with electrons, producing gamma rays that are detected by the scanner. This allows doctors to assess conditions like Alzheimer's disease and heart disease effectively.