Intraoperative radiotherapy (IORT) was performed in 20 of 36 patients with 
glioma; 11 glioblastomas, 7 malignant astrocytomas, 2 benign astrocytomas. 
Twenty or 25 Gy of irradiation was delivered in a single fraction 
intraoperatively, followed by external beam irradiation. The electron beam 
energy was selected so that the 80% isodose line fell at 2 or 3 cm below the 
residual tumor surface. Median survival time of IORT group was 14 months and 
that of the control group was 10 months. Difference of survival curve was 
significant. There were 6 incidences of complication caused by IORT; 1 
radionecrosis, 1 convulsion, 1 abscess, and 3 severe brain edemas. IORT is 
suited for the treatment of malignant gliomas.