title: Contouring variations and the role of atlas in non-small cell lung cancer radiation therapy: Analysis of a multi-institutional preclinical trial planning study.
abstract: OBJECTIVE
  To quantify variations in target and normal structure contouring and evaluate dosimetric impact of these variations in non-small cell lung cancer (NSCLC) cases. To study whether providing an atlas can reduce potential variation.
  
  
  METHODS
  Three NSCLC cases were distributed sequentially to multiple institutions for contouring and radiation therapy planning. No segmentation atlas was provided for the first 2 cases (Case 1 and Case 2). Contours were collected from submitted plans and consensus contour sets were generated. The volume variation among institution contours and the deviation of them from consensus contours were analyzed. The dose-volume histograms for individual institution plans were recalculated using consensus contours to quantify the dosimetric changes. An atlas containing targets and critical structures was constructed and was made available when the third case (Case 3) was distributed for planning. The contouring variability in the submitted plans of Case 3 was compared with that in first 2 cases.
  
  
  RESULTS
  Planning target volume (PTV) showed large variation among institutions. The PTV coverage in institutions' plans decreased dramatically when reevaluated using the consensus PTV contour. The PTV contouring consistency did not show improvement with atlas use in Case 3. For normal structures, lung contours presented very good agreement, while the brachial plexus showed the largest variation. The consistency of esophagus and heart contouring improved significantly (t test; P < .05) in Case 3. Major factors contributing to the contouring variation were identified through a survey questionnaire.
  
  
  CONCLUSIONS
  The amount of contouring variations in NSCLC cases was presented. Its impact on dosimetric parameters can be significant. The segmentation atlas improved the contour agreement for esophagus and heart, but not for the PTV in this study. Quality assurance of contouring is essential for a successful multi-institutional clinical trial.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina. Electronic address: yunfeng.cui@duke.edu.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Wenzhou
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, Georgia Regents University, Augusta, Georgia.
authors.forename: Feng-Ming Spring
authors.initials: FM
authors.lastname: Kong
authors.affiliation: Department of Radiation Oncology, Washington University, St Louis, Missouri.
authors.forename: Lindsey A
authors.initials: LA
authors.lastname: Olsen
authors.affiliation: Department of Radiation Oncology, M.S. Hershey Medical Center, Hershey, Pennsylvania.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Beatty
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, California.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Timothy
authors.initials: T
authors.lastname: Ritter
authors.affiliation: Department of Radiation Oncology, Case Western University, Cleveland, Ohio.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Sohn
authors.affiliation: Department of Radiation Oncology, Princess Margaret Hospital, Toronto, Ontario, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Higgins
authors.affiliation: Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania; Radiation Therapy Oncology Group, American College of Radiology, Philadelphia, Pennsylvania.
authors.forename: James M
authors.initials: JM
authors.lastname: Galvin
authors.affiliation: Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania; Radiation Therapy Oncology Group, American College of Radiology, Philadelphia, Pennsylvania.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiao
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed