title: Delineation variation of lymph node stations for treatment planning in lung cancer radiotherapy.
abstract: OBJECTIVE
  To assess the variability among clinicians in the delineation of mediastinal and hilar lymph node stations (LNS) according to the published recommendations in the treatment planning of elective nodal irradiation for lung cancer.
  
  
  METHODS
  Nine observers delineated on axial CT scans of five cases the LNS according to the guidelines of the published Atlas. Next, the Volumes of Consensus (VC)--fitting strictly the guidelines--for each LNS and case were collectively defined. Volume of Intersection (VI) as the overlap of the Delineated Volume (DV) for each LNS, case and observer with respective VC was computed. The Concordance Index (CI) for respective LNS and observers was defined as "VI/VC x 100%". The Discordance Index (DI) for respective LNS and observers was defined as "(1-VI/VD) x 100%".
  
  
  RESULTS
  Mean values of CI and DI for all observers were 69% and 36%, respectively. For five radiation oncologists who used to work as a team the ways of delineation were similar. The poorest reproducibility was shown for LNS 5, 7, 10R, and 10L.
  
  
  CONCLUSIONS
  Although detailed guidelines are used there is still substantial room for improvement. More training in the use of the Atlas is recommended.
authors.affiliation: Department of Radiation Oncology, M. Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, ul. Roentgena 5, Warsaw, Poland. lucynak@coi.pl
authors.forename: Lucyna
authors.initials: L
authors.lastname: Kepka
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Bujko
authors.forename: Dariusz
authors.initials: D
authors.lastname: Garmol
authors.forename: Jakub
authors.initials: J
authors.lastname: Palucki
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zolciak-Siwinska
authors.forename: Zuzanna
authors.initials: Z
authors.lastname: Guzel-Szczepiorkowska
authors.forename: Lucyna
authors.initials: L
authors.lastname: Pietrzak
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Komosinska
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Sprawka
authors.forename: Anna
authors.initials: A
authors.lastname: Garbaczewska
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008198:Lymph Nodes / Q000033:anatomy & histology*; D008220:Lymphography; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed