title: Quality of patient positioning during cerebral tomotherapy irradiation using different mask systems.
abstract: OBJECTIVE
  Patient immobilization during brain tumor radiotherapy is achieved by employing different mask systems. Two innovative mask systems were developed to minimize the problems of claustrophobic patients. Our aim was to evaluate whether the quality of patient immobilization using the new mask systems was equivalent to the standard mask system currently in use.
  
  
  METHODS
  Thirty-three patients with cerebral target volumes were irradiated using the Hi-Art II tomotherapy system between 2010 and 2012. Each group of 11 patients was fitted with one of the two new mask systems (Crystal® or Open Face® mask, Orfit) or the standard three-point mask (Raycast®-HP, Orfit) and a total of 557 radiotherapy fractions were evaluated. After positioning was checked by MV-CT, the necessary table adjustments were noted. Data were analyzed by comparing the groups, and safety margins were calculated for nonimage-guided irradiation.
  
  
  RESULTS
  The mean values of the table adjustments were: (a) lateral (mm): - 0.22 (mask 1, standard deviation (σ): 2.15); 1.1 (mask 2, σ: 2.4); - 0.64 (mask 3, σ: 2.9); (b) longitudinal (mm): - 1 (mask 1, σ: 2.57); - 0.5 (mask 2, σ: 4.7); - 1.22 (mask 3, σ: 2.52); (c) vertical (mm): 0.62 (mask 1, σ: 0.63); 1.2 (mask 2, σ: 1.0); 0.57 (mask 3, σ: 0.28); (d) roll: 0.35° (mask 1, σ: 0.75); 0° (mask 2, σ: 0.8); 0.02° (mask 3, σ: 1.12). The outcomes suggest necessary safety margins of 5.49-7.38 mm (lateral), 5.4-6.56 mm (longitudinal), 0.82-3.9 mm (vertical), and 1.93-4.5° (roll). There were no significant differences between the groups.
  
  
  CONCLUSIONS
  The new mask systems improve patient comfort while providing consistent patient positioning.
authors: Radiologische Klinik, FE Strahlentherapie, Universitätsklinik Bonn, Sigmund-Freud-Str. 25, 53105, Bonn, Germany, christina.leitzen@ukb.uni-bonn.de.
authors: C
authors: C
authors: Leitzen
authors: T
authors: T
authors: Wilhelm-Buchstab
authors: S
authors: S
authors: Garbe
authors: C
authors: C
authors: Lütter
authors: T
authors: T
authors: Müdder
authors: B
authors: B
authors: Simon
authors: H H
authors: HH
authors: Schild
authors: H
authors: H
authors: Schüller
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005858:Germany; D006801:Humans; D007103:Immobilization / Q000295:instrumentation* / Q000592:standards*; D008397:Masks / Q000592:standards*; D056888:Patient Positioning / Q000295:instrumentation* / Q000592:standards*; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity