title: Evaluation of an atlas-based automatic segmentation software for the delineation of brain organs at risk in a radiation therapy clinical context.
abstract: OBJECTIVE
  Conformal radiation therapy techniques require the delineation of volumes of interest, a time-consuming and operator-dependent task. In this work, we aimed to evaluate the potential interest of an atlas-based automatic segmentation software (ABAS) of brain organs at risk (OAR), when used under our clinical conditions.
  
  
  METHODS
  Automatic and manual segmentations of the eyes, optic nerves, optic chiasm, pituitary gland, brain stem and cerebellum of 11 patients on T1-weighted magnetic resonance, 3-mm thick slice images were compared using the Dice similarity coefficient (DSC). The sensitivity and specificity of the ABAS were also computed and analysed from a radiotherapy point of view by splitting the ROC (Receiver Operating Characteristic) space into four sub-regions.
  
  
  RESULTS
  Automatic segmentation of OAR was achieved in 7-8 min. Excellent agreement was obtained between automatic and manual delineations for organs exceeding 7 cm3: the DSC was greater than 0.8. For smaller structures, the DSC was lower than 0.41.
  
  
  CONCLUSIONS
  These tests demonstrated that this ABAS is a robust and reliable tool for automatic delineation of large structures under clinical conditions in our daily practice, even though the small structures must continue to be delineated manually by an expert.
authors.affiliation: Service de Physique, Institut Gustave Roussy, Villejuif, France. aurelie.isambert@igr.fr
authors.forename: Aurélie
authors.initials: A
authors.lastname: Isambert
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dhermain
authors.forename: François
authors.initials: F
authors.lastname: Bidault
authors.forename: Olivier
authors.initials: O
authors.lastname: Commowick
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Bondiau
authors.forename: Grégoire
authors.initials: G
authors.lastname: Malandain
authors.forename: Dimitri
authors.initials: D
authors.lastname: Lefkopoulos
mesh_terms: D000465:Algorithms; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012984:Software; D014057:Tomography, X-Ray Computed