How to observe the clinical effect of Gamma Knife: Gamma Knife is a kind of radiation therapy. It is not like a surgical operation that can immediately remove the diseased tissues, and the part to be treated has a longer process of metamorphosis and necrosis after receiving a one-time irradiation, which can be generally divided into three stages: (1) necrosis stage: 3 – 4 weeks after the treatment, the irradiated tissues have acute degenerative changes and inflammatory reactions; (2) absorption stage: after the necrosis stage and up to one year after the irradiation, the irradiated tissues’ cellular cleavage fragments are gradually absorbed. glial cell proliferation, vascular occlusion, endothelial cell proliferation, and the emergence of new capillaries; (3) late stage: can last for several years, during which the inflammatory reaction disappears, collagen scar formation, and no more new capillaries are formed. Therefore, the effect of Gamma Knife treatment is continuous and gradual, so it can not be evaluated on the basis of the situation at the time of treatment. For example, generally benign tumors do not increase in size after irradiation, shrink significantly after 3 C 6 months, and the patient’s clinical symptoms improve significantly or even disappear. Patients can undergo a review several months after gamma knife treatment and observe the process of improvement and gradual disappearance of symptoms.