title: Interobserver variability in clinical target volume delineation for primary mediastinal B-cell lymphoma.
abstract: OBJECTIVE
  The purpose of this study was to evaluate interobserver variability among radiation oncologists with experience in the field of lymphoma radiation therapy in the delineation of clinical target volume (CTV) in a challenging case of primary mediastinal B-cell lymphoma.
  
  
  METHODS
  Ten experienced radiation oncologists were invited to a 1-day contouring session. The case of a 56-year-old man with primary mediastinal B-cell lymphoma with complete metabolic response after chemotherapy was chosen as the sample for the study. A brief presentation of his clinical history was given, together with guidelines for contouring. The 10 CTVs obtained were then compared in terms of variation in total volume and in craniocaudal, laterolateral, and anteroposterior diameters. The CTV with the best Dice similarity coefficient (DSC) between the union of all 10 CTVs and the individual CTV was considered the reference CTV, and the DSC and the Hausdorff distance (HD) for each volume compared with the reference CTV were then calculated.
  
  
  RESULTS
  A significant variability was found in total volume (mean, 498.3 cm(3); range, 181.8-1003 cm(3)) and craniocaudal (median, 144.7 mm; range, 80.6-159 mm), laterolateral (median, 133.5 mm; range, 83.7-149.5 mm), and anteroposterior diameters (median, 136.2 mm; range, 84-150.5 mm). Analysis of the DSC and the HD showed a mean DSC of 0.53 (range, 0.31-0.74) and a mean HD of 6.4 cm (range, 1.8-14.8 cm).
  
  
  CONCLUSIONS
  Results of this study strongly indicate the need to develop and share appropriate contouring guidelines among experts and suggest the promotion of specific educational activities to improve radiation therapy quality in both clinical trials and routine clinical practice.
authors.affiliation: Department of Oncology, University of Torino, Turin, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Piva
authors.affiliation: Department of Radiation Oncology, University of Chieti, SS Annunziata Hospital, Chieti, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Genovesi
authors.affiliation: Department of Oncology, University of Torino, Turin, Italy. Electronic address: andreariccardo.filippi@unito.it.
authors.forename: Andrea Riccardo
authors.initials: AR
authors.lastname: Filippi
authors.affiliation: Radiotherapy Department, Radiation Oncology, Catholic University, Rome, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Balducci
authors.affiliation: Radiation Oncology, Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy.
authors.forename: Salvina
authors.initials: S
authors.lastname: Barra
authors.affiliation: Radiation Oncology, University of Brescia, Brescia, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Buglione
authors.affiliation: Radiotherapy Unit, Ospedale dell'Angelo, Mestre, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Busetto
authors.affiliation: Department of Oncology and Advanced Technology, Radiation Therapy Unit, Arcispedale S. Maria Nuova Hospital-Istituto di Ricovero e Cura a Carattere Scientifico, Reggio Emilia, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Ciammella
authors.affiliation: Radiation Oncology, Azienda Ospedaliera SS Antonio, Biagio e Cesare Arrigo, Alessandria, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Franzone
authors.affiliation: Radiation Oncology, Azienda Ospedaliera S. Andrea, La Sapienza University, Rome, Italy.
authors.forename: Vitaliana
authors.initials: V
authors.lastname: De Sanctis
authors.affiliation: Radiotherapy, University of Florence, Florence, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Simontacchi
authors.affiliation: Medical Physics, University of Torino, Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Fusella
authors.affiliation: Department of Oncology, University of Torino, Turin, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Ricardi
mesh_terms: D006801:Humans; D016393:Lymphoma, B-Cell / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008479:Mediastinal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D015588:Observer Variation; D017410:Practice Guidelines as Topic / Q000592:standards*; D018787:Radiation Oncology / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*