title: [Repositioning accuracy of cerebral fractionated stereotactic radiotherapy using CT scanning].
abstract: OBJECTIVE
  To evaluate the accuracy of patient repositioning in fractionated cerebral stereotactic radiotherapy using a Brain Lab stereotactic cranial mask in conjunction with standard dental fixation.
  
  
  METHODS
  Fifty planning and checking CT scans were performed in 25 patients. The check CT scan was performed before or after one of the three sessions of treatment. Coregistration to the planning CT scan was used to assess alignment of the isocentre to the reference markers. The relative position of the PTV with regard to isocentre allowed us to determine its total displacement (3D vector).
  
  
  RESULTS
  Mean isocentre translations (+/-SD) taking into account direction were -0.01+/-0.7, -0.2+/-1.3 and 0.07+/-0.5mm in mediolateral, craniocaudal and anteroposterior directions respectively. Mean rotations (+/- SD) were -0.02+/-0.6, -0.08+/-0.3 and -0.1+/-0.3 degree in mediolateral, craniocaudal and anteroposterior axes respectively. Mean overall PTV displacement was 1.8+/-1.5mm. PTV displacement was smaller than 2 and 3mm in 19/25 and 23/25 patients respectively.
  
  
  CONCLUSIONS
  The accuracy of patient positioning using a stereotactic cranial mask system is similar to those reported in the literature and shows a satisfactory reproducibility with a standard dental fixation.
authors.affiliation: Département universitaire de radiothérapie, centre O.-Lambret, Combemale, 59020 Lille, France. davidpasquier@free.fr
authors.forename: D
authors.initials: D
authors.lastname: Pasquier
authors.forename: F
authors.initials: F
authors.lastname: Dubus
authors.forename: B
authors.initials: B
authors.lastname: Castelain
authors.forename: M
authors.initials: M
authors.lastname: Delplanque
authors.forename: V
authors.initials: V
authors.lastname: Bernier
authors.forename: I
authors.initials: I
authors.lastname: Buchheit
authors.forename: C
authors.initials: C
authors.lastname: Kerr
authors.forename: I
authors.initials: I
authors.lastname: Santoro
authors.forename: A
authors.initials: A
authors.lastname: Huchet
authors.forename: N
authors.initials: N
authors.lastname: Causse
authors.forename: E
authors.initials: E
authors.lastname: Lartigau
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D006801:Humans; D007103:Immobilization / Q000295:instrumentation* / Q000379:methods; D008397:Masks; D055805:Moving and Lifting Patients; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods