I. Technical Overview To be precise, the gamma knife is a computer-controlled advanced radiation therapy equipment. Its gamma rays come from the cobalt 60 radiation source, using computer-controlled mechanical equipment equipped with the radiation source to produce precise movements, determine the location of the target area through MRI or PET-CT, irradiate the target area with multiple focused beams of gamma rays, and irradiate it with a single high dose or multiple conventional doses to achieve the purpose of killing the lesion, producing a good curative effect similar to surgical excision. It is more precise than traditional radiotherapy techniques to destroy cancer cells and protect normal tissues better. Therefore, the image is called “gamma knife”. The advent of the gamma knife poses a great challenge to surgery. Because of the small damage and good efficacy, it has partially replaced surgery. Qingdao Central Hospital Radiotherapy Department Zhang Xiaotao Gamma knife in the medical professional standard name is: stereotactic radiosurgery (radiotherapy), the English abbreviation: SRS or SRT. technically gamma knife belongs to the category of radiation oncology, the use of radiation to kill the lesion. Unlike conventional radiotherapy, the Gamma Knife is classified as a new generation of precision radiotherapy, as is conformal intensity modulated radiotherapy. Stereotactic radiotherapy is divided into head gamma knife and body gamma knife according to the implementation site, the latter is the professional standard name: SBRT (Stereotactic body radiation therapy), SBRT can also be achieved by the new generation of linear gas pedals (speed light knife true-beam, radio wave knife cyber-knife). An important direction at present is the integration of stereotactic radiotherapy technology and intensity modulated radiotherapy technology on the same device, i.e. the same device can implement the above two technologies. Second, the characteristics of gamma knife 1, without surgery can be “removed” intracranial lesions, without the risk of surgical treatment. 2, simple and time-saving, a single treatment takes only 30 to 40 minutes. 3.The treatment is precise, with small error and little damage to the surrounding normal tissues. 4.It has higher biological effective dose than traditional radiotherapy, i.e. higher efficacy of killing tumor. 5.Under the guidance of CT, MRI, DSA or PET-CT images, Gamma Knife adopts computer control and automates the treatment procedure, reducing human errors and making it precise and easy to compare. 6.For screened cases, the efficacy appears faster and better than conventional dose of radiotherapy. Third, stereotactic radiosurgery technology (commonly known as the gamma knife) the general principles of adaptation 1, applicable to the lesion nature is clear, can be determined by medical imaging technology, to completely kill the lesion for the purpose of treatment. 2, not suitable for the lesion range can not be defined for preventive treatment. Therefore, the gamma knife is not a universal device, need to strictly grasp the indications. 3, different treatment purposes for the size and number of lesions suitable for gamma knife requirements are different. Theoretically, the smaller the lesion, the greater the possibility of complete elimination. (A) head indications 1, intracranial AVM, pituitary tumor, auditory neuroma, meningioma, solid or mixed but mainly solid craniopharyngioma, pineal tumor, jugular venous bullae, malignant tumor and other benign tumors; 2, intracranial metastatic tumors (preferred), astrocytoma, ventricular meningioma, medulloblastoma, oligodendroglioma, nasopharyngeal carcinoma residual or local recurrent lesions. 3. Functional diseases: trigeminal neuralgia, Parkinson’s disease, intractable epilepsy. (II) Body indications 1.Primary and metastatic lung cancer (isolated lung cancer for which the patient does not choose surgery or for which the patient is not eligible for surgery) 2.Primary or metastatic liver cancer, local recurrence of rectal cancer, primary and metastatic kidney cancer, adrenal tumor, pancreatic cancer, prostate cancer and prostatic hypertrophy, etc. 3.Isolated single or multiple metastatic lymph nodes. 4.Palliative treatment for the purpose of symptom relief, the indications should be determined according to the actual lesion. IV. Assessment of treatment feasibility 1. The pathological diagnosis should be obtained as much as possible before treatment of the primary lesion to reduce the chance of misdiagnosis and misdiagnosis; 2. The patient’s cardiopulmonary function can be satisfied by lying down for about 30 min (depending on the duration of treatment); 3. The patient can lie down quietly to cooperate with treatment; 4. CT, MRI or PET-CT examinations that can be performed; 5. No acute bleeding, asthma attack and acute heart disease are expected; 6. , pre-treatment assessment of the expected efficacy must be greater than the treatment of injury, the principle that injury should be minimized, the injury can be saved or be informed of the non-salvageable, and the therapeutic injury is medically acceptable and in line with medical ethics.