gms | German Medical Science

63rd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Japanese Neurosurgical Society (JNS)

German Society of Neurosurgery (DGNC)

13 - 16 June 2012, Leipzig

Matched pair analysis of mask-based and mask-less radiosurgery for benign intracranial tumors

Meeting Abstract

  • O. Blanck - Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Campus Lübeck; CyberKnife Zentrum Norddeutschland
  • S. Seifert - CyberKnife Zentrum Norddeutschland
  • D. Rasche - Klinik für Neurochirurgie, Universitätsklinikum Schleswig-Holstein, Campus Lübeck
  • D. Rades - Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Campus Lübeck
  • G. Hildebrandt - Klinik für Strahlentherapie, Universitätsklinikum Rostock
  • V. Tronnier - Klinik für Neurochirurgie, Universitätsklinikum Schleswig-Holstein, Campus Lübeck

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 63. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie (JNS). Leipzig, 13.-16.06.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. DocP 087

doi: 10.3205/12dgnc474, urn:nbn:de:0183-12dgnc4749

Published: June 4, 2012

© 2012 Blanck et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: To precisely guide the high dose beams during radiosurgery for intracranial tumors two methodologies exist: A stereotactic frame which is attached to the patients’ skull as coordinate system (GammaKnife™, Elekta, Sweden) and x-ray image guidance with immobilization devices such as thermoplastic masks (Novalis™, BrainLab, Germany and CyberKnife™, Accuray, USA). In addition the CyberKnife may be used without immobilization devices due to its high localization frequency during treatment to enhance patient comfort. In this study we analyzed the accuracy of using x-ray guidance with and without immobilization devices.

Methods: In our institution we generally treat benign intracranial tumors in 3 fractions with either a thermoplastic mask or a head rest (both Unger, Germany) depending on the patients' preference after detailed risk education. For this study we analyzed the treatment accuracy of 10 patients in a matched pair setting where we matched tumor location, treatment plan, Karnofsky performance index and age. We then evaluated inter beam patient maximum motion, total average localization error, imaging frequency, treatment interruptions, treatment prolongation and short-term outcome.

Results: The maximum patients' inter beam motion for all 15 fractions was 0.55 mm / 1.02 degree with the mask and 0.78 mm / 0.88 degree without the mask. The total average localization error per beam was 0.06 mm / 0.10 degree and 0.11 mm / 0.14 degree, respectively. The average image frequency was 2.6 beams per image and 2.5 beams per image, respectively. The total average fraction treatment time was 27.3 min for all patients. The treatment fraction prolongation compared to the simulated treatment time was in average 1 minute with 0.4 interruptions with the mask and 2 minutes with 1.7 without the mask. The setup time was in average 13 minutes and 10 minutes respectively. Both groups were evaluated 3 months after treatment showing no difference in response. All tumors were locally controlled and all patients had symptoms relief where symptoms such as headache and dizziness were present. No procedure related side effects were reported.

Conclusions: The radiosurgery treatment of benign intracranial tumors with the CyberKnife in general proves to be highly effective and precise. We additionally evaluated a new method for an improved patient comfort and similar accuracy as the general method. The new “mask-free” method was well accepted by the patients especially by those with tendencies of claustrophobia.