title: Relocatable fixation systems in intracranial stereotactic radiotherapy. Accuracy of serial CT scans and patient acceptance in a randomized design.
abstract: OBJECTIVE
  The goal was to provide a quantitative evaluation of the accuracy of three different fixation systems for stereotactic radiotherapy and to evaluate patients' acceptance for all fixations.
  
  
  METHODS
  A total of 16 consecutive patients with brain tumours undergoing fractionated stereotactic radiotherapy (SCRT) were enrolled after informed consent (Clinical trials.gov: NCT00181350). Fixation systems evaluated were the BrainLAB® mask, with and without custom made bite-block (fixations S and A) and a homemade neck support with bite-block (fixation B) based on the BrainLAB® frame. The sequence of measurements was evaluated in a randomized manner with a cross-over design and patients' acceptance by a questionnaire.
  
  
  RESULTS
  The mean three-dimensional (3D) displacement and standard deviations were 1.16 ± 0.68 mm for fixation S, 1.92 ± 1.28 and 1.70 ± 0.83 mm for fixations A and B, respectively. There was a significant improvement of the overall alignment (3D vector) when using the standard fixation instead of fixation A or B in the craniocaudal direction (p = 0.037). Rotational deviations were significantly less for the standard fixation S in relation to fixations A (p = 0.005) and B (p = 0.03). EPI imaging with off-line correction further improved reproducibility. Five out of 8 patients preferred the neck support with the bite-block.
  
  
  CONCLUSIONS
  The mask fixation system in conjunction with a bite-block is the most accurate fixation for SCRT reducing craniocaudal and rotational movements. Patients favoured the more comfortable but less accurate neck support. To optimize the accuracy of SCRT, additional regular portal imaging is warranted.
authors.affiliation: Department of Radiation-Oncology (MAASTRO), GROW (School for Oncology & Developmental Biology), Maastricht University Medical Centre, Dr Tanslaan 12, 6229, Maastricht, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Theelen
authors.forename: J
authors.initials: J
authors.lastname: Martens
authors.forename: G
authors.initials: G
authors.lastname: Bosmans
authors.forename: R
authors.initials: R
authors.lastname: Houben
authors.forename: J J
authors.initials: JJ
authors.lastname: Jager
authors.forename: I
authors.initials: I
authors.lastname: Rutten
authors.forename: P
authors.initials: P
authors.lastname: Lambin
authors.forename: A W
authors.initials: AW
authors.lastname: Minken
authors.forename: B G
authors.initials: BG
authors.lastname: Baumert
mesh_terms: D000236:Adenoma / Q000601:surgery*; D016477:Artifacts; D001254:Astrocytoma / Q000601:surgery; D001932:Brain Neoplasms / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008577:Meningeal Neoplasms / Q000601:surgery; D008579:Meningioma / Q000601:surgery; D009426:Netherlands; D009464:Neuroma, Acoustic / Q000601:surgery; D010342:Patient Acceptance of Health Care; D056888:Patient Positioning / Q000295:instrumentation*; D010911:Pituitary Neoplasms / Q000601:surgery; D011446:Prospective Studies; D016634:Radiosurgery / Q000295:instrumentation*; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation*; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*