ABSTRACT
PURPOSE: To evaluate the role of linac based radiosurgery (RS) in the treatment of meningiomas, we retrospectively analyzed the results of clinical and follow up CT/MRI studies. METHODS AND MATERIALS: From the 1988 July to 1998 April, twenty patients of meningioma had been treated with 6 MV linear accelerator based radiosurgery. Of the 20 patients, four (20%) were male and 16 (80%) were female. Mean age was 51 years old (22~78 years old). Majority of intracranial location of tumor for RS were parasagittal and sphenoid wing area. RS was done for primary treatment in 6 (30%), postoperative residual lesions in 11 (55%) and regrowth after surgery in 3 (15%). Mean tumor volume was 5.72 cm3 (0.78~15.1 cm3) and secondary collimator size was 2.04 cm (1~3 cm). The periphery of tumor margin was prescribed with the mean dose of 19.6 Gy (9~30 Gy) which was 40~90% of the tumor center dose. The follow up duration ranged from 2.5 to 109 months (median 53 months). Annual CT/MRI scan was checked. RESULTS: By the follow up imaging studies, the tumor volume was reduced in 5 cases (25%), arrested growth in 14 cases (70%), and increased size in 1 case (15%). Among these responsive and stable 19 patients by imaging studies, there showed loss of contrast enhancement after CT/MRI in four patients. In clinical response, nine (45%) patients were considered improved condition, 10 (50%) patients were stable and one (5%) was worsened to be operated. This partly resulted in necrosis after surgery. CONCLUSION: The overall control rate of meningiomas with linac based RS was 95% by both imaging follow-up and clinical evaluation. With this results, linac based RS is considered safe and effective treatment method for meningioma.