Gamma Knife can be used as a treatment for early limited tumors and metastases of lung and liver that are inoperable due to advanced age or medical reasons. Stereotactic body radiation therapy (SBRT) is a kind of non-surgical radiosurgery treatment that uses γ-rays to complete stereotactic body radiation therapy (SBRT) technology. Body γ-knife is to focus 18-47 cobalt sources (the number of sources varies among different models) with 6000-9000Ci energy on one point through rotational focusing. By rotating and focusing multiple beams of γ-rays, the lesion receives a continuous high dose, while the surrounding normal tissue receives a transient low dose, thus achieving the purpose of high dose in the target area and low dose outside the target area. The selection of body γ-knife treatment should be based on the tumor size, location, tumor pathology type and patient’s body condition and other factors. It is mainly suitable for the treatment of tumors of essential organs such as lung, liver and pancreas, and the treatment includes radical radiotherapy, additional radiotherapy after conventional radiotherapy and recurrent radiotherapy after radiotherapy. Early limited tumors or metastases of lung and liver can be treated with γ-knife to obtain radical effect, and compared with surgical treatment, γ-knife has less damage and fewer complications. Thus, γ-knife can be one of the treatments for early limited tumors and metastases of lung and liver that cannot be operated due to advanced age or medical reasons. When the tumor is large and there is regional lymph gland metastasis, it should be considered combined with other radiotherapy and chemotherapy according to the situation. γ knife irradiation dose and fractionation methods vary according to the size and location of the tumor, there is no uniform standard, the total fractionation amount is larger than conventional radiotherapy, some use alternate day irradiation, some use continuous irradiation. CTV), and the preventive irradiation of lymph glands in the drainage area is appropriate for adjuvant conventional radiotherapy or chemotherapy. Body gamma knife is suitable for treating tumors in the essential organs and tumors in the cavernous organs and areas distant from the spinal cord, such as primary and metastatic tumors in the lung, liver, pancreas, kidney, adrenal gland, prostate, retroperitoneum, anterior mediastinum, and pre-corporeal region. In clinical practice, it is mainly used for the treatment of lung cancer, abdominal lymph gland metastasis, biliary tract cancer, prostate cancer, lung metastasis, pelvic lymph gland metastasis, retroperitoneal tumor, liver cancer, pancreatic cancer, liver metastasis, and presacral recurrence after rectal cancer surgery. At present, among the cases treated by gamma knife in the national statistics, those with higher proportion in order are peripheral type lung cancer, retroperitoneal lymph gland metastasis, liver cancer, pancreatic cancer, liver metastasis, lung metastasis, etc. In principle, the treatment effect is good for small tumor size and regular shape, while the treatment effect is relatively poor for tumor >6cm and irregular shape. Body γ-knife treatment should be avoided as much as possible when there are some cases as follows: 1. Tumor is accompanied by large amount of pleural effusion or ascites. Tumors located in or adjacent to cavity organs, such as esophageal cancer, colon cancer, cardia cancer, gastric cancer, etc. (except for local recurrence of rectal cancer after rerouting surgery). Tumors in the abdominal cavity have adhesions with the intestinal canal, etc. Tumors in these areas are prone to radiation damage, bleeding, perforation and stenosis of normal cavity organs when treated with gamma knife. 3.Tumors with late stage body failure. 4.Tumor is huge with extensive metastasis and the treatment cannot benefit the patient. There are many factors affecting the efficacy of γ-knife treatment, besides the general condition, age, clinical stage and pathological type of the patient, the size of the tumor and whether the organ in which it is located allows high-dose irradiation is the most important. Most of the patients currently treated with γ-knife have large tumors or are estimated to be unresectable by surgery or have contraindications to surgery or the patient refuses surgery. Even so, the local control rate for tumors smaller than 5 cm in essential organs such as liver and lung can reach more than 90%, but the follow-up time for treatment of these tumors is still relatively short, and the long-term survival rate remains to be statistically analyzed by long-term follow-up results.