title: Dosimetric comparison of different treatment modalities for stereotactic radiosurgery of meningioma.
abstract: BACKGROUND
  The objective of this study was to compare the three most prominent systems for stereotactic radiosurgery in terms of dosimetric characteristics: the Cyberknife system, the Gamma Knife Perfexion and the Novalis system.
  
  
  METHODS
  Ten patients treated for recurrent grade I meningioma after surgery using the Cyberknife system were identified; the Cyberknife contours were exported and comparative treatment plans were generated for the Novalis system and Gamma Knife Perfexion. Dosimetric values were compared with respect to coverage, conformity index (CI), gradient index (GI) and beam-on time (BOT).
  
  
  RESULTS
  All three systems showed comparable results in terms of coverage. The Gamma Knife and the Cyberknife system showed significantly higher levels of conformity than the Novalis system (Cyberknife vs Novalis, p = 0.002; Gamma Knife vs Novalis, p = 0.002). The Gamma Knife showed significantly steeper gradients compared with the Novalis and the Cyberknife system (Gamma Knife vs Novalis, p = 0.014; Gamma Knife vs Cyberknife, p = 0.002) and significantly longer beam-on times than the other two systems (BOT = 66 ± 21.3 min, Gamma Knife vs Novalis, p = 0.002; Gamma Knife vs Cyberknife, p = 0.002).
  
  
  CONCLUSIONS
  The multiple focal entry systems (Gamma Knife and Cyberknife) achieve higher conformity than the Novalis system. The Gamma Knife delivers the steepest dose gradient of all examined systems. However, the Gamma Knife is known to require long beam-on times, and despite worse dose gradients, LINAC-based systems (Novalis and Cyberknife) offer image verification at the time of treatment delivery.
authors.affiliation: Department of Radiation Oncology, Charité School of Medicine and University Hospital, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany, david.kaul@charite.de.
authors.forename: David
authors.initials: D
authors.lastname: Kaul
authors.forename: Harun
authors.initials: H
authors.lastname: Badakhshi
authors.forename: Thierry
authors.initials: T
authors.lastname: Gevaert
authors.forename: Diana
authors.initials: D
authors.lastname: Pasemann
authors.forename: Volker
authors.initials: V
authors.lastname: Budach
authors.forename: Constantin
authors.initials: C
authors.lastname: Tuleasca
authors.forename: Constantin
authors.initials: C
authors.lastname: Tulaesca
authors.forename: Arne
authors.initials: A
authors.lastname: Gruen
authors.forename: Vikas
authors.initials: V
authors.lastname: Prasad
authors.forename: Marc
authors.initials: M
authors.lastname: Levivier
authors.forename: Markus
authors.initials: M
authors.lastname: Kufeld
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000601:surgery*; D008579:Meningioma / Q000601:surgery*; D008875:Middle Aged; D011874:Radiometry; D016634:Radiosurgery / Q000295:instrumentation / Q000379:methods*