[The development of radiosurgery--introduction of the gamma knife for brain lesions]

In 1990, the first gamma unit in Asia was installed at Tokyo University Hospital. This article describes the radiosurgical techniques used and clinical experiences during treatment of 70 cases at the unit. Stereotactic radiosurgery using a gamma knife for the treatment of AVM, CPA tumor and meningioma has been used for more than 20 years. With this form of therapy, a high dose of radiation is delivered from multi-directional beams to deep lesions of the brain, incurring only minimal radiation exposure at the periphery. When a large dose of radiation is applied to a small area, there may be certain side effects especially if care is not taken. Accordingly, treatment of brain lesions using a gamma knife requires teamwork, even though it appears to be a safe procedure at the present time.