PET-CT stands for Positron Emission Computed Tomography, which can obtain tomographic images of all aspects of the body. It has the advantages of early detection of diseases, safety and non-invasiveness. PET-CT is a fusion of PET and CT, which allows detailed and precise anatomical localization and displays tomographic images of the entire body. The advantages of PET-CT include early diagnosis of diseases, such as early tumors, etc.; it is safe and non-invasive; it can make the test results more accurate; and the test results can be reported quickly. It is suitable for patients with long-term diseases, such as chronic hepatitis, atrophic gastritis, etc.; people with a family history of tumors, such as lung cancer, breast cancer, stomach cancer, etc.. It is also suitable for the diagnosis of some degenerative diseases, such as Parkinson’s disease, Alzheimer’s disease and so on.