The cranial gamma knife is the most representative instrument of stereotactic radiosurgery (SRS). Stereotactic radiosurgery and stereotactic radiotherapy (SRT) literally have two different words, one is “surgery” and the other is “treatment”, which determines They are fundamentally different. Stereotactic Radiation Therapy (SRT) is based on the previous general radiation therapy technology and developed by using the principle of stereotactic radiosurgery. The main equipment includes X-knife, whole body gamma knife, linear gas pedal 3 dimensional conformal radiation therapy (3DCRT) and intensity modulated radiation therapy (IMRT) and other equipment and techniques. Gamma knife stereotactic radiosurgery is characterized by three-dimensional, small-field, focused, single, high-dose irradiation, while SRT is three-dimensional, small-field, focused, multiple, high-dose irradiation. The differences are mainly in the positioning accuracy, the quality of the radiation focus, and the number of treatments and doses. The reason for these differences is that although these devices also use stereotactic technology to determine the coordinates of the target location of the lesion and treat the lesion by means of ray focusing, the positioning of the lesion is usually fixed by head and face or body models, and one positioning is used repeatedly to meet the needs of multiple radiation treatments, which also determines that the positioning of the SRT lesion is not very accurate. More importantly, due to the difference in radiation focus, the attenuation of radiation dose outside the target area is not as steep as that of cranial gamma knife, in the case of the same dose in the center of the lesion, the normal brain tissue around the lesion is irradiated by radiation dose is larger than that of cranial gamma knife, so SRT for the sake of safety, usually use multiple larger doses (larger than ordinary radiotherapy dose, smaller than the dose of gamma knife) irradiation. In contrast, cranial gamma knife uses cranial fixed positioning, radiation focusing ability is stronger, the attenuation gradient of radiation dose outside the target area is very steep, using a single high-dose irradiation does not harm the normal tissue around the lesion, and the radiobiological effect produced by single and multiple irradiation is also very different, which is also the reason why cranial gamma knife can play a good curative effect on benign tumors that are not sensitive to conventional radiotherapy. For these reasons, SRT is not yet as “surgical” as the cranial gamma knife, which is “therapeutic”. However, SRT also represents the development direction of radiation therapy for tumors in the world today. For malignant tumors, especially those in the body, radiation therapy does not need to reach the degree of “surgery” like cranial gamma knife, but only needs to be “precise”, because there is tumor cell invasion in the subclinical lesions around the tumor, and irradiation of this part is necessary. It is also necessary to irradiate this part of the tissue, which is of great significance to prevent recurrence and metastasis. The great significance of stereotactic radiotherapy is that the treatment scope of stereotactic radiotherapy has been developed to the whole body, so that the radiotherapy for body tumors has also been obtained to a more precise degree, and the linear gas pedal can not only conformal, but also intensity modulation treatment, and it is also equipped with respiratory gating technology (a technology to ensure precise treatment in the respiratory state), which is also not available in other radiotherapy equipment. For high-grade malignant glioma, the efficacy is greatly improved and the side effects and complications are reduced compared to the previous general radiotherapy. However, for the majority of small intracranial lesions and lesions in special intracranial areas such as the saddle area and brainstem, especially benign intracranial tumors and cerebral arteriovenous malformations and other cranial diseases are good indications for cranial gamma knife SRT, which is the most suitable for cranial gamma knife treatment, and some diseases are even irreplaceable by other radiotherapy devices.