[Prospects and future: evolution of stereotactic methodology for planning]

We have been using the stereotactic methodology of Talairach for Linac radiosurgery of cerebral arteriovenous malformations since 1984, and updated it with addition of CT and MR images into the stereotactic space. The target remains defined, as in most other centers, by stereotactic angiography. However, tridimensional configuration of cerebral arteriovenous malformations is better defined using MR or CT-angiography. Therefore, pre-radiosurgical imaging tends to combine multimodal images oriented into the stereotactic space. Frame-based radiosurgery, with invasive frame placement, will be replaced in the future by frameless irradiation with real-time tracking of the patients head, as performed by the recently described Cyber-knife. Intraoperative X-ray will be no longer long-distance fixed equipments but mobile, short-distance fluoroscopic systems integrated in the surgical workstation environment. Finally, biplane conventional angiography performed for cerebral arteriovenous malformations identification will be replaced by CT and MR-angiography, except in some cases who could still require DSA for accurate target identification.