Nuclear medicine is a peaceful use of nuclear technology, which is fundamentally different from nuclear weapons. In our daily life, all kinds of radiation are everywhere: television, computers, cell phones and even decorative materials used at home; in hospitals, in addition to the nuclear medicine department, the imaging examination (including X-ray filming, CT, etc.), radiotherapy department, etc. are all using all kinds of rays to diagnose and treat the diseases for patients. The amount of radiopharmaceuticals used in the process of nuclear medicine diagnosis and treatment is strictly controlled within the scope of absolute safety and as little as possible, so it can be said that nuclear medicine is very safe, in fact, the amount of radiation suffered by the patient in the nuclear medicine examination is less than half of the amount of radiation suffered by the CT examination of the same part or even lower. Most of the radiologic agents are usually eliminated from the body within a few hours, or at most 1-2 days, and side effects are rare. The small dose of radiation a patient receives is negligible compared to the benefits of an early, accurate diagnosis of disease after a nuclear medicine exam. Is radionuclide therapy safe? The nuclide used in radionuclide therapy can only be absorbed by specific diseased tissues, retaining the nuclide, and other tissues will not be harmed because they do not absorb the nuclide or seldom absorb the nuclide. 2. The therapeutic rays emitted by the nuclides absorbed by the diseased tissues (most commonly used in the form of beta rays) have a very short effective range in the body and will not harm the surrounding normal tissues or will cause slight injuries (which can be recovered). 3. The state has strict management regulations for radionuclides, and only under the condition of ensuring the safety of doctors and patients can the patients be treated with radionuclides. 4. Before accepting radionuclide treatment, nuclear medicine doctors should study the patient’s medical history in detail to determine whether it is suitable for radionuclide treatment, and then decide the treatment plan and dose according to the actual situation of the patient 5. The sensitivity of normal tissue cells to rays is much lower than that of the tumor cells: in general, the greater the activity of cell division is, the more sensitive it is to the rays, and the greater the ability to concentrate the radionuclide, so the rays will destroy or inhibit the diseased tissues and at the same time, the normal tissues will not be affected by radiations. Therefore, the rays can destroy or inhibit the lesion tissues, and at the same time, the normal tissues can not be affected or only slightly affected. A large number of clinical reports show that nuclide therapy does not cause cancer, infertility, congenital malformation of children, etc. Therefore, nuclide therapy is very safe. Therefore, nuclide therapy is a very safe and reliable treatment method. However, nuclide therapy is not recommended for pregnant women and children.