Nuclear medicine is the study of the application of atomic nuclear technology in medicine and its theory. The daily work of nuclear medicine cannot be separated from radionuclides and nuclear rays. As a result of the application of atomic nuclear technology in the war, people on the rays of the general existence of a kind of fear, even including some medical personnel, including the knowledge of nuclear medicine is relatively poor, suffering from fear of “nuclear” disease, talk about “nuclear” color change. Nuclear medicine is really so dangerous? In fact, for nuclear medicine and nuclear weapons, we can use natural phenomena to play an analogy: the same meteorological rainfall, spring rain in the spring to moisturize the earth, giving rise to the infinite vitality of the spring; and the summer has a great destructive power of hail, tornadoes will only bring disaster to the earth and mankind. Nuclear medicine is like the spring rain, and nuclear weapons are like hailstones and hurricanes; due to the different radiation doses, the impact of these two on human beings is very different. The low-dose rays used in nuclear medicine are absolutely safe, not only will it not bring damage to human beings, but on the contrary, it opens up a new way of diagnosis and treatment for human beings. What’s more, human beings themselves live in a world full of rays, only that we don’t know about it. Each of us at any time and anywhere with the ray “close contact”, although invisible and unnoticeable, but are unknowingly withstand the radiation of the ray of irradiation: cosmic rays from space everywhere in the air over us; the earth’s soil, rocks and water sources also exists in trace amounts of natural radionuclides; in the production of human beings, consumption activities, but also produce radioactivity, for example, we watch TV programs every day, the television tube, the television, the television, the television, the television, the television, the television, the television, the television, the television, the television and the television. Television programs, television tubes by high-speed electronic bombardment, there will be a trace of radiation generated, in addition, cell phones, computers and so on will have a trace of radiation. All this constitutes the basic radiation we call the radioactive background. Relative to these existing radioactive sources, the radiation dose brought about by nuclear medicine is not a significant increase, and thus will not cause harm to the examinee, and in the process of nuclear medicine diagnosis and treatment of radiopharmaceuticals used in the dosage itself are strictly controlled within the scope of absolute safety, it can be said that nuclear medicine is very safe. As an emerging discipline, nuclear medicine has great advantages in medical applications: in medical tracing research, it is a sensitive and accurate tracing technology; for quantitative analysis of biologically active substances, it provides highly specific means of ultra-micro analysis; diagnosis, it will be the organic combination of functional and morphological examination, reflecting the overall and local functions, and dynamically observing the pathological changes caused by diseases. Therapeutically, it is a novel and effective treatment method. As nuclear medicine has all the above advantages, and is simple, economical and non-invasive, it is widely used in various disciplines and specialties of medical science, and has made great contributions to the development of modern medicine.