The present paper represents the first clinical report of the use of stereotactically-directed narrow beams of helium ions from the 184-inch Synchrocyclotron at the Lawrence Berkeley Laboratory for the radiosurgical treatment of life-threatening vascular disorders of the brain, including inoperable or inaccessible deep arteriovenous malformations (AVMs) and carotid artery-cavernous sinus fistulas ( CCFs ). We describe the methods developed for stereotactic neuroradiological imaging and stereotactic helium-ion Bragg peak radiosurgery in the evaluation and treatment of the first 55 patients with deep AVMs in a clinical research protocol. We discuss the diagnosis and epidemiological characteristics of the diseases, the neurosurgical and radiosurgical methods of treatment available and the initial experience of stereotactic helium-ion Bragg peak radiosurgery , including stereotactic neuroradiological evaluation, treatment planning, heavy-ion beams, patient treatment protocol, early clinical results, patient evaluation and follow-up studies planned, and conclusions thus far obtained.