title: Geometrical verification system using Adobe Photoshop in radiotherapy.
abstract: OBJECTIVE
  Adobe Photoshop is used worldwide and is useful for comparing portal films with simulation films. It is possible to scan images and then view them simultaneously with this software. The purpose of this study was to assess the accuracy of a geometrical verification system using Adobe Photoshop.
  
  
  METHODS
  We prepared the following two conditions for verification. Under one condition, films were hanged on light boxes, and examiners measured distances between the isocenter on simulation films and that on portal films by adjusting the bony structures. Under the other condition, films were scanned into a computer and displayed using Adobe Photoshop, and examiners measured distances between the isocenter on simulation films and those on portal films by adjusting the bony structures. To obtain control data, lead balls were used as a fiducial point for matching the films accurately. The errors, defined as the differences between the control data and the measurement data, were assessed.
  
  
  RESULTS
  Errors of the data obtained using Adobe Photoshop were significantly smaller than those of the data obtained from films on light boxes (p < 0.007).
  
  
  CONCLUSIONS
  The geometrical verification system using Adobe Photoshop is available on any PC with this software and is useful for improving the accuracy of verification.
authors.affiliation: Department of Radiology, Kitasato University Hospital, Kanagawa, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Ishiyama
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Keiji
authors.initials: K
authors.lastname: Niino
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hosoya
authors.forename: Kazushige
authors.initials: K
authors.lastname: Hayakawa
mesh_terms: D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012984:Software