[1] European Cyberknife Ctr, Max Lebsche Pl 31, D-81377 Munich, Germany
[2] Univ Hosp Cologne, Ctr Neurosurg, Dept Stereotaxy & Funct Neurosurg, Cologne, Germany
[3] Ludwig Maximilians Univ Munchen, Dept Neurosurg, Campus Grosshadern, Munich, Germany
[4] German CyberKnife Ctr, Soest, Germany
[5] CyberKnife Ctr Mitteldeutschland, Erfurt, Germany
[6] Charite Univ Med Berlin, Charite CyberKnife Ctr, Berlin, Germany
[7] CyberKnife Sudwest, Radiochirurgicum, Goppingen, Germany
[8] Ludwig Maximilians Univ Munchen, Dept Otorhinolaryngol & Head & Neck Surg, Campus Grosshadern, Munich, Germany