Gamma knife or Gamma ray treatment is a kind of radiation therapy (where radiation is being delivered through a separate kind of precision oriented mechanism). This kind of treatment is suitable for a variety of lesions and some of the main factors that determine its usage would be - the site of the lesion and the size of the lesion besides the pathological nature. In astrocytoma, the treatment depends on the site, size and the grade of the tumour, with a combination of surgery (as complete an excision as possible) and radiotherapy (with use of any of the different modes of delivery of radiation) plus chemotherapy as an option for high grade tumours. Gamma knife is being done in north India in Delhi in AIIMS and VIMHANS, in Bangalore, in Madras to name a few places. X-knife is similar to gamma knife and is being offered at AIIMS and Apollo, Delhi along with some centres in the south as well.
Of course, to be able to say as to what is the combination of modalities ideally suitable for any particular patient, one has to study the case and individualise appropriate treatment.