title: Alternated prone and supine whole-breast irradiation using IMRT: setup precision, respiratory movement and treatment time.
abstract: OBJECTIVE
  The objective of this study was to compare setup precision, respiration-related breast movement and treatment time between prone and supine positions for whole-breast irradiation.
  
  
  METHODS
  Ten patients with early-stage breast carcinoma after breast-conserving surgery were treated with prone and supine whole breast-irradiation in a daily alternating schedule. Setup precision was monitored using cone-beam computed tomography (CBCT) imaging. Respiration-related breast movement in the vertical direction was assessed by magnetic sensors. The time needed for patient setup and for the CBCT procedure, the beam time, and the length of the whole treatment slot were also recorded.
  
  
  RESULTS
  Random and systematic errors were not significantly different between positions in individual patients for each of the three axes (left-right, longitudinal, and vertical). Respiration-related movement was smaller in prone position, but about 80% of observations showed amplitudes <1 mm in both positions. Treatment slots were longer in prone position (21.2 ± 2.5 min) than in supine position (19.4 ± 0.8 min; p = 0.044).
  
  
  CONCLUSIONS
  Comparison of setup precision between prone and supine position in the same patient showed no significant differences in random and systematic errors. Respiratory movement was smaller in prone position. The longer treatment slots in prone position can probably be attributed to the higher repositioning need.
authors.affiliation: Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium. Liv.Veldeman@uzgent.be
authors.forename: Liv
authors.initials: L
authors.lastname: Veldeman
authors.forename: Werner
authors.initials: W
authors.lastname: De Gersem
authors.forename: Bruno
authors.initials: B
authors.lastname: Speleers
authors.forename: Bart
authors.initials: B
authors.lastname: Truyens
authors.forename: Annick
authors.initials: A
authors.lastname: Van Greveling
authors.forename: Rudy
authors.initials: R
authors.lastname: Van den Broecke
authors.forename: Wilfried
authors.initials: W
authors.lastname: De Neve
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009068:Movement; D009929:Organ Size; D058958:Organs at Risk / Q000528:radiation effects; D056888:Patient Positioning; D016684:Prone Position; D011832:Radiation Injuries / Q000517:prevention & control; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration; D016683:Supine Position; D013997:Time Factors