1. Department of Medical Physics, School of Medicine, University of Patras, University Campus, 26504 Rio Achaia, Greece
2. Department of Neurosurgery, School of Medicine, University of Patras, University Campus, 26504 Rio Achaia, Greece
3. Department of Neurosurgery, University Hospital of Patras, 265 04 Rio Achaia, Greece
4. Department of Medical Physics, University Hospital of Patras, 26504 Rio Achaia, Greece