Nuclear medicine, also known as nucleology, is a medical specialty that uses radioactive substances to diagnose and treat diseases. Unlike traditional radiology, which records radiation transmitted through the body from external sources like X-ray generators, nuclear imaging records radiation emitted from within the body. The focus of nuclear medicine scans is on the function of organs and tissues rather than their anatomy. This is why it is referred to as a physiological imaging modality. Nuclear medicine utilises two primary imaging modalities, single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans. These are commonly used in the field. It is important to note that SPECT and PET scans are the two most common imaging modalities in nuclear medicine.