title: Delineation of the larynx as organ at risk in radiotherapy: a contouring course within "Rete Oncologica Piemonte-Valle d'Aosta" network to reduce inter- and intraobserver variability.
abstract: OBJECTIVE
  To evaluate the usefulness of a contouring course in reducing inter- and intraobserver variability in the definition of the larynx as organ at risk (OAR).
  
  
  METHODS
  Within the "Rete Oncologica Piemonte-Valle d'Aosta" network, a contouring course focusing on larynx delineation was proposed. Twenty-six radiotherapist technicians (RTTs) experienced in delineating OARs were asked to contour larynx before and after the training. An expert radiation oncologist defined the reference volume for educational purpose. The contoured volumes obtained before and after the course were compared using descriptive statistics (mean value, standard deviation-SD, and coefficient of variation-COV) of volumes and maximum diameters. Conformity index (CI), dice coefficient (DC), and percentage of overlap were used to evaluate the spatial accuracy of the different volumes compared to the reference. Further analysis regarding the variation in the centre of mass (COM) displacement was performed.
  
  
  RESULTS
  The mean volume was 40.4 cm3before and 65.9 cm3after the course, approaching the reference value. Mean anteroposterior, laterolateral, and craniocaudal diameters improved, getting each closer to the reference. Moreover, the COM moved approaching reference coordinates. Mean percentage of intersection and DC strongly increased after the course, rising from 57.76 to 93.83 % and from 0.68 to 0.89, respectively. CI enhanced from 0.06 to 0.31.
  
  
  CONCLUSIONS
  This study shows an improvement in larynx definition after the contouring course with lower interobserver variability and major consistency compared to the reference volume. Other specific educational activities may further increase the quality of radiation therapy contouring in this setting.
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy. domecante@yahoo.it.
authors.forename: Domenico
authors.identifier: http://orcid.org/0000-0002-8155-6865
authors.initials: D
authors.lastname: Cante
authors.affiliation: Medical Physics Department, A.S.L. TO4, Ivrea, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Petrucci
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Piva
authors.affiliation: Medical Physics Department, A.S.L. TO4, Ivrea, Italy.
authors.forename: Valeria Casanova
authors.initials: VC
authors.lastname: Borca
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy.
authors.forename: Piera
authors.initials: P
authors.lastname: Sciacero
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bertodatto
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Marta
authors.affiliation: Department of Oncology, Radiation Oncology, University of Torino, Turin, Italy.
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Franco
authors.affiliation: Department of Rete Oncologica Piemonte e Valle d'Aosta, Turin, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Viale
authors.affiliation: Local Health Authority Turin 4 (A.S.L. TO4), Turin, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: La Valle
authors.affiliation: Radiotherapy Department, Ivrea Community Hospital, A.S.L. TO4, Ivrea, Italy.
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: La Porta
authors.affiliation: Department of Rete Oncologica Piemonte e Valle d'Aosta, Turin, Italy.
authors.forename: Oscar
authors.initials: O
authors.lastname: Bertetto
mesh_terms: D006801:Humans; D007558:Italy; D007830:Larynx / Q000528:radiation effects*; D015588:Observer Variation; D058958:Organs at Risk / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
keywords: Contouring; Course; Larynx; Radiotherapy