title: Interobserver variations of target volume delineation in multicatheter partial breast brachytherapy after open cavity surgery.
abstract: OBJECTIVE
  To investigate interobserver variations of target volume delineations in accelerated partial breast irradiation with multicatheter brachytherapy (BT) and to assess the impact of guidelines on consistency of contouring.
  
  
  METHODS
  A contouring study with two phases in interstitial accelerated partial breast irradiation after open cavity surgery was conducted by the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology Breast Cancer Working Group. Contours of cavity and planning target volume (PTV) on preimplant and postimplant CT images were delineated. In Phase 1, nine radiation oncologists defined the target volumes of 5 patients, whereas in Phase 2, four observers draw the contours of 4 patients applying guidelines. In Phase 1, experience in breast BT after open cavity surgery was assessed. The delineations were compared between Phase 1 and Phase 2, the impact of guidelines was assessed, and cavity visualization score was related to consistency of delineations.
  
  
  RESULTS
  Significant interobserver variability in delineations of lumpectomy cavity and PTV was observed among the participants. Observers with BT experience after open cavity surgery outlined the cavity and PTV more consistently (conformity indexgen: 0.52 vs. 0.48 and 0.59 vs. 0.55 for preimplant and postimplant cavities). For all volumes, the mean Vmax/Vmin was 2.2 vs. 2.8. Having used guidelines all conformity indices increased significantly. For cavity, the increase was 14% and 11%, whereas for the PTV, 28% and 17% on the preimplant and postimplant CT images, respectively. A strong correlation was found between consistency of contours and cavity visualization score.
  
  
  CONCLUSIONS
  Simple guidelines on defining the lumpectomy cavity significantly increased the consistency of contouring. Reliable consistency of target volume definition can be expected only for good cavity visibility.
authors.affiliation: Radiotherapy Centre, National Institute of Oncology, Budapest, Hungary. Electronic address: major@oncol.hu.
authors.forename: Tibor
authors.initials: T
authors.lastname: Major
authors.affiliation: Department of Radiation Oncology, Catalan Institute of Oncology, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gutiérrez
authors.affiliation: Radiation Oncology, Institute IMOR, Barcelona, Spain.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Guix
authors.affiliation: Institut of Radiooncology and Radiotherapy, Landesklinikum Wiener Neustadt, Wiener Neustadt, Austria.
authors.forename: Emőke
authors.initials: E
authors.lastname: Mózsa
authors.affiliation: Department of Radiation Oncology, Centre Antoine Lacassagne, Nice, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Hannoun-Levi
authors.affiliation: Department of Radiation Oncology, Inselspital-Bern University Hospital, Bern, Switzerland.
authors.forename: Kristine
authors.initials: K
authors.lastname: Lössl
authors.affiliation: Department of Radiotherapy, Muncipal Hospital Cologne, Cologne, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Niehoff
authors.affiliation: Department of Radiotherapy and Radiobiology, University Hospital AKH Vienna, Vienna, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Resch
authors.affiliation: Department of Radiotherapy, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: van Limbergen
authors.affiliation: Radiotherapy Centre, National Institute of Oncology, Budapest, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Polgár
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery*; D057785:Catheters; D002983:Clinical Competence; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D015588:Observer Variation; D017410:Practice Guidelines as Topic; D018787:Radiation Oncology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: Breast brachytherapy; Cavity delineation; Cavity visualization; Interobserver variation