A 3-D RADIOSURGICAL METHODOLOGY FOR COMPLEX ARTERIOVENOUS-MALFORMATIONS

A 3-D methodology, the associated targets methodology, for planning radiosurgical irradiations of complex arteriovenous malformations (AVMs) is presented. It uses the ARTEMIS-3D treatment planning system and has been devised and adopted by our group since January 1990. Its main features are: (a) prescription and delivery of a minimal target dose on the surface of the lesion, corresponding to a 60-70% isodose range. The dose to adjacent functional neurological structures is taken into account as well as the maximum dose to the lesion; (b) An optimisation approach consisting of obtaining the optimal superimposition of the isodose surface and the 3-D contour of the lesion and sharp fall-offs by interactive manipulation of the treatment parameters. The clinical choice of the treatment plan is based on a compromise between the optimal reference isodose surface encompassing the lesion and the minimisation of the volumetric dose fall-off. In complex AVMs the angiographic results have been significantly improved in comparison with our previous experience because of the better achieved lesion encompassing.