Nuclear medicine is a discipline that uses radiopharmaceuticals to diagnose and treat diseases and conducts medical research, and is an important aspect of mankind’s peaceful use of atomic energy. The mission of nuclear medicine is to diagnose, treat and study diseases using nuclear techniques. Nuclear medicine diagnostic techniques include organ imaging, functional assays and in vitro radioimmunoassays. When performing organ imaging and/or functional assays, the physician, depending on the purpose of the examination, gives the patient an oral or intravenous injection of a radioactive tracer that enters the body and participates in the circulation and metabolism of specific organs and tissues in the body, and continuously emits radiation. In this way, we can track and investigate with various special detection instruments outside the body, and show the morphology and function of the patient’s internal organs in the form of numbers, images, curves or photographs. Nuclear medicine imaging methods are simple, sensitive, specific, non-invasive, safe (the radiation dose to the patient is lower than that of a single X-ray), easily reproducible, accurate and reliable, and reflect the function and metabolism of the organs, which is why they are increasingly used in clinical and basic research. The early and mature nuclear medicine treatments with good efficacy include 131 iodine for hyperthyroidism, differentiated thyroid cancer and its metastases, 89 strontium for bone metastases, and 90 strontium for capillary hemangioma.