Nuclear medicine is a medical specialty involving the use of small amounts of radioactive materials that are typically injected into the bloodstream, inhaled or swallowed to diagnose and treat diseases in a safe and painless way.

Nuclear medicine scans based on physiological function as opposed to the other diagnostic tests that determine the presence of a disease based on anatomy or structural appearance such as CT or MRI, for this reason, it is called a physiological imaging modality.

Nuclear medicine can use in many kinds of the area such as Oncology, Neuroimaging, Cardiology, Infection disease, Pharmacokinetics, Small animal imaging, Musculoskeletal imaging. Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) scans are the two most common imaging modalities in nuclear medicine.