I. Overview of Gamma Knife Dose Fractionation Therapy for Head: “Gamma Knife Dose Fractionation Therapy” is a new treatment concept and method, which belongs to a major new progress of Gamma Knife treatment. “Gamma Knife Dose Fractionation Therapy” not only retains the advantages of Gamma Knife high-dose focused irradiation, but also draws on the advantages of repeated irradiation of radiotherapy rays, which can greatly improve the control rate of tumors, but also reduce the damage to the normal brain. “Gamma Knife Dose Fractionation Therapy is suitable for all kinds of brain tumors, benign or malignant, especially for larger tumors. The common ones are glioma, metastatic tumor, meningioma, pituitary adenoma, acoustic neuroma and so on; there are also the less common ones such as intracerebral lymphoma, pineal region tumor, chordoma, osteochondroma, nasopharyngeal carcinoma, maxillary sinus carcinoma, intraorbital tumors and so on. Wang Hongwei, Neurosurgery Department, Inner Mongolia Medical University Hospital, Head Gamma Knife Dose Splitting for Brain Tumor Treatment “Surgery, radiotherapy and chemotherapy” are the three major treasures for the treatment of torso tumors. However, the treatment of brain tumor is still based on “surgery + gamma knife”. The main reason is that chemotherapy for brain tumors has very limited efficacy, while radiotherapy for brain tumors has always had the problem of large side effects. Although the head gamma knife also belongs to the category of radiotherapy, it has been transformed into a non-general radiotherapy, which is a precise radiotherapy guided by stereotactic technology, and belongs to the category of stereotactic radiosurgery, and is the “gold standard” of stereotactic radiosurgery, and nowadays, the head gamma knife has already become the main means of treatment for brain tumors, and even has surpassed surgery for quite a number of patients. For a considerable number of patients, it has surpassed surgery and become the preferred treatment method. Gamma Knife dose fractionation therapy, on the basis of this new development. Advantages of Gamma Knife Dose Splitting Head Gamma Knife is superior to other equipments including X-knife, radio wave knife, tom knife, linear gas pedal, etc., and has become the “gold standard” of stereotactic radiosurgery for brain tumors, because Gamma Knife has three absolute advantages: (1) accurate and precise 3D localization; (2) unparalleled and unmatched positioning of the brain tumor; and (3) the ability to detect the brain tumor and to detect the brain tumor. (2) unparalleled three-dimensional spatial focusing of rays; and (3) highly consistent three-dimensional conformity of tumors. Head Gamma Knife Dose Splitting Therapy, while possessing these three advantages, also changes the one-time high dose irradiation of head Gamma Knife into medium dose irradiation with multiple repetitions. This improvement makes the head Gamma Knife treatment not only suitable for smaller tumors, but also has satisfactory efficacy for larger tumors. The so-called “dose division” is to divide the lethal dose of the tumor into several parts for repeated irradiation. It has been commonly used in conventional radiotherapy for a long time, but there is no precedent for “head Gamma Knife dose fractionation therapy”. The problems and difficulties exist at three levels: (1) change of treatment concepts; (2) design of specific methods; and (3) summarization of actual experience. V. Theoretical basis of head gamma knife dose segmentation therapy Head gamma knife through stereotactic spatial focusing method, numerous beams of gamma rays all-round convergence on the tumor, for a one-time large-dose irradiation, so that the tumor degeneration necrosis, shrinkage and disappearance. It has the advantages of light trauma, short cycle and little pain. However, for larger brain tumors, this “one-time large-dose irradiation” will lead to obvious side effects, even intracranial hypertension. The radiobiological theory that “Head Gamma Knife Dose Splitting Therapy” can reduce these side effects is based on the following: (1) repeated irradiation can proliferate the tumor cells left over from the previous irradiation (reoxygenation of anaerobic dormant cells) and kill them; (2) since the tolerance dose of brain tissue to radiation is higher than that of tumor tissue, when the irradiation dose is lowered to between the two, the radiation dose will be lower than that of the tumor tissue, and the radiation dose will be reduced to between the two. When the irradiation dose is lowered to between the two, the radiation can lethally damage the tumor cells, but only produce sub-lethal damage to the normal brain tissue; the first kind of damage is irreversible, while the latter kind of damage can be repaired by itself in the inter-treatment period (more than 6 hours). The concept of “Gamma Knife Dose Splitting Therapy” is the result of the unremitting pursuit and exploration of Gamma Knife scholars, which brings new hope for Gamma Knife treatment of large brain tumors, and has proved to be of epoch-making significance.