title: Novalis frameless image-guided noninvasive radiosurgery: initial experience.
abstract: OBJECTIVE
  To evaluate our initial experience with Novalis (BrainLAB, Heimstetten, Germany) frameless image-guided noninvasive radiosurgery.
  
  
  METHODS
  The system combines the dedicated Novalis linear accelerator with ExacTrac X-Ray 6D, an infrared camera and a kilovolt stereoscopic x-ray imaging system, a noninvasive mask system, and ExacTrac robotics for patient positioning in six degrees of freedom. Reference cranial skeletal structures are radiographically imaged and automatically fused to digital reconstructed radiographs calculated from the treatment planning computed tomographic scan to find the target position and accomplish automatic real-time tracking before and during radiosurgery. We present the acceptance testing and initial experience in 15 patients with 19 intracranial lesions treated between December 2005 and June 2006 at the Charité by frameless image-guided radiosurgery with doses between 12 and 20 Gy prescribed to the target-encompassing isodose.
  
  
  RESULTS
  Phantom tests showed an overall system accuracy of 1.04 +/- 0.47 mm, with an average in-plane deviation of 0.02 +/- 0.96 mm for the x-axis and 0.02 +/- 0.70 mm for the y-axis. After infrared-guided patient setup of all patients, the overall average translational deviation determined by stereoscopic x-ray verification was 1.5 +/- 1.3 mm, and the overall average rotational deviation was 1.0 +/- 0.8 degree. The data used for radiosurgery, after stereoscopic x-ray verification and correction, demonstrated an overall average setup error of 0.31 +/- 0.26 mm for translation and 0.26 +/- 0.23 degree for rotation.
  
  
  CONCLUSIONS
  This initial evaluation demonstrates the system accuracy and feasibility of Novalis image-guided noninvasive radiosurgery for intracranial benign and malignant lesions.
authors.affiliation: Department of Radiation Oncology, Charité Campus Mitte, Charité-Universitätsmedizin Berlin, Berlin, Germany. Reinhard.Wurm@charite.de
authors.forename: Reinhard E
authors.initials: RE
authors.lastname: Wurm
authors.forename: Stephan
authors.initials: S
authors.lastname: Erbel
authors.forename: Isabel
authors.initials: I
authors.lastname: Schwenkert
authors.forename: Franz
authors.initials: F
authors.lastname: Gum
authors.forename: Daniel
authors.initials: D
authors.lastname: Agaoglu
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schild
authors.forename: Lorenz
authors.initials: L
authors.lastname: Schlenger
authors.forename: Dirk
authors.initials: D
authors.lastname: Scheffler
authors.forename: Mario
authors.initials: M
authors.lastname: Brock
authors.forename: Volker
authors.initials: V
authors.lastname: Budach
mesh_terms: D001932:Brain Neoplasms / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D038361:Neuronavigation / Q000295:instrumentation / Q000379:methods*; D016634:Radiosurgery / Q000295:instrumentation / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D012371:Robotics / Q000295:instrumentation / Q000379:methods