Nuclear imaging is a medical technique that helps doctors see inside the body using small amounts of radioactive materials. These materials, called radiotracers, are injected, swallowed, or inhaled, and they emit energy that can be detected by special cameras. This allows healthcare professionals to visualize organs and tissues, helping them diagnose conditions like cancer or heart disease. The images produced by nuclear imaging provide valuable information about how well organs are functioning. For example, a PET scan (Positron Emission Tomography) can show how active certain areas of the brain are, while a SPECT scan (Single Photon Emission Computed Tomography) can assess blood flow in the heart.