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