PET-CT is a very efficient medical examination technology, it has high imaging, high accuracy, non-invasive, effective and safe technology, its characteristics are mainly: 1, to identify whether the lump is benign or malignant tumor. 2, can quickly locate the location area of malignant tumor in the body and quickly find the tumor. 3, before the tumor forms a lump, it is still in the cellular state to screen whether it is malignant tumor. 4. It can be used as a review indicator of malignant tumor after treatment, but the disadvantage is that it is expensive and there are relatively few places where PET-CT can be done.