Radionuclides and rays are inseparable from the daily work of nuclear medicine. Due to the improper use of nuclear technology, which has brought great harm to human beings, people have a general fear of radiation. We often see patients do a chest X-ray, CT, or even several or several parts of the CT examination can be very happy to accept, but do a nuclear medicine examination is very difficult to make up your mind, even including some medical personnel, due to the lack of knowledge of nuclear medicine, also often talk about “nuclear” fear, think that nuclear medicine examination will make the human body suffer from The belief is that nuclear medicine tests can cause radiation damage, cancer, or even mutations. Are nuclear medicine tests really that “scary”? First of all, we should know that radiation from various kinds of rays in daily life is everywhere: there are many natural radionuclides in the natural air and soil, so that we have to receive background exposure every day; the use of television, computers, cell phones and other home life will also expose us to a certain dose of radiation; a long-distance air flight may be much higher than the radiation received by a nuclear medicine examination …… and compared to these existing radioactive sources, the radiation dose brought by nuclear medicine examination is not significantly increased, because the dosage of radioactive drugs used in the process of nuclear medicine treatment is strictly controlled within the absolute safety range, which will not cause radiation damage to the examinees. Secondly, the activity of the radioactive drugs injected into the patient’s body decreases with time. The radionuclides used in nuclear medicine examination are all short half-life radionuclides, among which the physical half-life of technetium-99m labeled imaging agent used in SPECT imaging is 6 hours, plus the metabolism and excretion of the drug from the body, generally the effective half-life in the patient’s body is at most 2-3 hours, while the physical half-life of fluorine-18 labeled imaging agent used in PET/CT imaging is only 110 minutes. The physical half-life is only 110 minutes. Studies have confirmed that radiation measurements of the patient’s surroundings are only higher within 0.5 hours and at a distance of 0.5 meters after injection of the imaging agent, while measurements after 1 hour and at a distance of more than 1 meter decrease rapidly. Although we routinely instruct the patient to avoid close contact with infants and pregnant women on the day of the examination, in fact the radioactivity in the patient’s body has mostly subsided after the examination is completed in the nuclear medicine department, and generally does not affect the people in close contact with them. Since radiopharmaceuticals have high biological detection sensitivity, require very little chemical dosage compared to CT or MR contrast agents, do not disturb the equilibrium of physiological processes in the body, and usually have no allergic reactions. After the injection of nuclear imaging agent, it will not interfere with other imaging examinations (such as ultrasound, CT, MR, etc.) and will not affect the results of various in vitro analysis tests (except for in vitro radiological analysis method). With the development of medical technology, nuclear functional imaging represented by molecular imaging is more and more widely used in early diagnosis, staging, prognosis and efficacy observation of diseases, etc. Currently, one in three patients in developed countries use nuclear medicine examination in treatment. However, the application of nuclear medicine technology in China lags far behind that of developed countries. We should look at the radiation problem of nuclear medicine rationally, recognize the well-being of human beings brought by radionuclides, and use nuclear medicine technology reasonably in clinical and scientific research practice to promote the improvement of diagnosis and treatment of diseases.