Proton three-demensional conformal radiosurgery of arteriovenous malformation of the brain.

The proton beam radiosurgery was performed to 65 patients with brain AVM since December, 2001 till February, 2012, in Joint Institute for Nuclear Research, Dubna, Russia. We have analyzed data for 56 patients. The follow up time varied from 24 to 109 months. The volumes of brain AVMs varied from 0.92 to 82 cc. The mean isocenter dose was 24.61 +/- 0.12 Gy E. The edge of the target was included in 70-90% isodose. The proton beam surgery was splitted in two similar doses and delivered in two consecutive days in vast majority of patients. Ten patients were missed for follow up due to some reasons. The radiosurgery was resulted in full obliteration of AVM in 23 from remaining 46 (50%) patients. There was full obliteration in 46.6% of patients with volume of AVM 10-24.9 cc; and this rate is significantly more than for photon radiosurgery of same size brain AVM. The partial obliteration was obtained in 21 patients. Only one patients suffered hemorrhage from partially obliterated AVM. We could not see any effect in 2 patients. There were delayed radiation toxicity in 5 patients in 12 months after treatment: in 4 patients, these reactions were assessed as 2 according to RTOG scale and were dissipated in 1 month after commencement of corticosteroid treatment. There was radiation necrosis in one patient, and it was relieved in 12 months after several courses of dehydration and corticosteroid therapy. So, proton beam therapy is effective and safe modality for treatment of inoperable brain AVM, especially of middle- and large size.