1.Patients with confirmed malignant tumor: PET-CT can accurately stage lesions, clarify whether there are metastases in other organs, help choose treatment plan, and avoid inappropriate surgery and treatment. 2.Patients with malignant tumor under treatment and after treatment: evaluate treatment effect, monitor recurrence and metastasis after tumor surgery and radiotherapy, and distinguish tumor from scar tissue. 3.Patients who find metastatic lesions but unknown primary lesions: 4.Tumor Suspected patients: If tumor markers are increased, CT and MRI find lesions but cannot clarify the nature, PET-CT can characterize a variety of lesions. 5.Patients with family history of tumor: Patients with certain chronic diseases, long-term smoking, alcoholism or mental stress. 6.Patients with epilepsy: PET-CT can find epileptogenic foci in the brain, locate them and then perform surgery or radiotherapy to cure epilepsy. 7. Patients with myocardial infarction or severe myocardial ischemia: PET-CT is the most reliable method to determine whether the myocardium at the site of myocardial infarction is alive or not, which is directly related to whether one can receive coronary artery grafting and intracoronary angioplasty, and to estimate the prognosis of the surgery. 8. Health checkups for people over 40 years old.