Osama S. Abdelaziz is Professor of Neurosurgery at the Faculty of Medicine of the Alexandria University, Egypt. He is Director of Alexandria Stereotactic Radiosurgery Center and Member of the International Stereotactic Radiosurgery Society (ISRS). He is Treasurer of the Egyptian Society of Skull Base Surgery (ESSBS) and Board member of the Egyptian Stereotactic and Functional Neurosurgery Group (ESFNS). He is Past-Fellow at Harvard University, USA, University of California Los Angeles (UCLA), USA, and Shiga University of Medical Science, Japan. Antonio A.F. De Salles is Professor Emeritus in the Neurosurgery and Radiotherapy Departments of the University of California Los Angeles (UCLA), USA. He is Director and Founder of NeuroSapiens, Brazil. He is Past-President of the International Stereotactic Radiosurgery Society (ISRS) and Past-President and Founder of Ibero-Latin-American Radiosurgery Society.