1. Department of Neurosurgery, University Hospital Leipzig, University of Leipzig, 04103 Leipzig, Germany
2. Department of Radiation Oncology, University Hospital Leipzig, University of Leipzig, 04103 Leipzig, Germany
3. Department of Neuropathology, University Hospital Leipzig, University of Leipzig, 04103 Leipzig, Germany
4. Fraunhofer Institute for Machine Tools and Forming Technology, Theodor-Koerner-Allee 6, 02763 Zittau, Germany