PET-CT is the medical examiner with the highest diagnostic accuracy in the world. PET-CT is an organic combination of PET and CT technologies to form an image workstation. Therefore, PET-CT has the functions of PET, CT and the fusion of PET and CT images, forming a complete and most advanced imaging system. Patients can obtain both CT anatomical images and PET functional metabolism images through rapid whole-body scanning during the examination, and these two images complement each other to make a comprehensive and accurate judgment of the disease, for example, the accuracy rate of PET-CT in the examination of lung cancer can reach more than 90%.