In order to avoid the damage of ordinary extracranial radiation to normal brain tissues of brain tumor patients and improve the therapeutic efficacy, intra-tumor radiotherapy is often applied nowadays. Compared with ordinary extracranial radiation therapy, intracranial radiotherapy for brain tumor has the features of improving lesion absorbed dose and nuclide activity, shortening treatment time, improving effective dose, protecting normal brain cells and reducing brain tissue damage. 1.Improve lesion absorbed dose and nuclide activity Intratumor radiotherapy can improve lesion absorbed dose and nuclide activity, so that the absorbed dose of nuclide activity given to lesion tissue can reach the nuclide activity needed for cure. 2, shortening treatment time With intracranial radiotherapy for brain tumor and stereotactic surgery for radioactive isotope placement, the cumulative daily radiation dose received by the patient can be as much as 10-15Gy, which shortens the treatment time compared with ordinary intracranial radiation, and the radiation dose received locally by the brain tumor is obviously more than that received by the surrounding brain tissues. 3.Implantation of isotope in brain tumor does not consider the cell cycle of the tumor and irradiates the tumor continuously, which improves the effective degree of dose. Protecting normal brain tissue cells Radiotherapy for brain tumor belongs to the category of low radiation rate and high radiation dose, which is conducive to the repair of reversible radiation damage by normal brain tissue cells. Reducing brain tissue damage When intracranial radiotherapy for brain tumor is treated with low radiation rate, the anaerobic cells of the tumor can be changed into oxygenated cells, which improves the therapeutic effect of the brain tumor and reduces the radioactive damage of the brain tissue.