STEREOTAXICALLY GUIDED RADIOSURGERY USING THE LINEAR-ACCELERATOR

Leksell initiated the concept of stereotactic radiosurgery in 1951. Th is last decade has seen a rapid proliferation in the development of th e methodology which is certainly related in part to the simultaneous g rowth of high-resolution neuro-imaging techniques. By focusing the bea ms of 201 hemispherically arrayed cobalt 60 sources, the gamma-knife d elivers a high dose of radiation to a small target. Another possibilit y proposed by several authors is the bragg peak cyclotron-generated ir radiation with accelerated protons or helium ions. In Lille, since 198 8, we have choosen to develop stereotactic radiosurgery, according to the system of Betti, by the association of Talairach's stereotactic me thodology and external single-dose encephalic irradiation with high en ergy X-rays, delivered by means of a linear accelerator. The major ind ication for the use of this method is an arteriovenous malformation. S tereotactic radiosurgery may be proposed alone or in combination with surgery and embolisation. It has been shown to be a potentially effect ive treatment and an attractive alternative in carefully selected pati ents with intracranial tumours: slow-growing, well limited, deep-seate d tumours, such as some gliomas, acoustic neurinomas, skull base menin giomas, pituitary adenomas. This treatment is also used to deliver a f ocal boost of radiation to previously administered fractionated radiot herapy in patients with small gliomas and solitary brain metastases.