PET-CT examination is an important treatment tool commonly used in clinical practice to detect tumors, identify the nature of tumors and perform pathological staging. If there is a local tumor in the body, the tumor will often be hypermetabolic to glucose, so that after using a certain contrast agent, this hypermetabolic material will form hypermetabolic foci in the tumor through blood circulation, and then the location of the tumor can be detected by lung CT or body CT. Of course, PET-CT is an imaging test, which can only play the role of suggesting the diagnosis of tumor, and the accuracy rate of tumor diagnosis is about 80%. For the high generation lesions found by PET-CT, further pathological clarification is needed to confirm whether it is a tumor or what kind of tumor, and of course, it can also be used to evaluate the efficacy of tumor treatment afterwards. If PET-CT has high metabolism before tumor treatment, and after treatment PET-CT has significantly reduced metabolism, it means that tumor treatment is effective, especially in the treatment of lymphoma, PET-CT is used to evaluate the efficacy, and it is written in the guidelines.