[Clinical evaluation of intraoperative radiotherapy using photon radiosurgery system for brain tumors].

The photon radiosurgery system is a miniature X-ray generator that can be placed stereotactically and intraoperatively into intracranial tumors to deliver a single fraction of high-dose interstitial irradiation. This battery-powered device produces low energy X-ray photons in a spherical and symmetrical pattern at the probe tip. Dose rates of up to 200 cGy/Mim are possible, allowing for the administration of 15 Gy to a lesion 3 cm in diameter in less than 1 hr. Background exposure is minimal, and no special shielding of the patient or health care personnel is required. Thirty-nine patients with brain tumor were treated in this method. There were no adverse effects. During the follow-up period of 1-30 months, 3 cases with 5 metastatic brain tumors died about 8 months after this treatment. Five recurrent cases of 21 malignant gliomas died about 4 months after treatment. Interstitial radiotherapy using photon the radiosurgery system promises to be a useful treatment for brain tumors.