Optimisation in stereotactic radiosurgery of AVMs: II. Comparison of arc and MMLC therapy.

Two stereotactic surgery methods, arc and micro-multileave collimator (MMLC) therapy, were compared in the particular case of arteriovenous malformations (AVMs) treatment. Different methods of the treatment optimisation were used. The comparison covered a group of 22 patients suffering from peripheral and central AVMs of different sizes who underwent initially arc therapy. Several parameters were evaluated to compare the two methods: 2D and 3D isodose representations, dose-volume histograms (DVHs) and probability of success. The 3D isodoses were compared for the 22 patients showing a better conformity for the MMLC (three cases are presented). The DVHs of the AVM were also in favour of MMLC. In terms of probability of success, the results showed that are therapy was superior only in the case of small spherical lesions. MMLC therapy proved to be superior to arc therapy in all cases but central spherical small volume AVMs.