CT with shadows is a common understanding of the images on CT films. There are many kinds of shadows, such as they can be metal artifacts, normal tissue or abnormal tissue. Some patients do not remove metal objects from their body before the examination, such as necklaces, bracelets, watches, metal buttons or belts on their clothes, etc. After the examination, there will be metal-like artifacts on the machine film, and some of them will affect the diagnosis result. Some other people have tissue congenital mutations, which will have some differences from the normal structure of others, and must be judged by professional doctors before they can be judged as normal or not. Other patients have truly abnormal tissue, which can be inflammatory, tuberculosis, tumors or other conditions that must be professionally diagnosed by a physician.