title: Interobserver variability in radiation therapy plan output: Results of a single-institution study.
abstract: OBJECTIVE
  We investigated the sources of variability in radiation therapy treatment plan output between planners within a single institution.
  
  
  METHODS
  Forty treatment planners across 5 campuses of an institution created a plan on the same thoracic esophagus patient computed tomography scan and structure set. Plans were scored and ranked based on the planner's adherence to an ordered list of target dose coverage and normal tissue evaluation criteria. A runs test was used to identify whether any of the studied planner qualities influenced the ranking. Spearman rank correlation was used to investigate whether plan score correlated with years of experience or planned monitor units.
  
  
  RESULTS
  The distribution of scores, ranging from 80.24 to 135.89, was negatively skewed (mean, 128.7; median, 131.5). No statistically significant relationship between plan score and campus (P = .193), job title (P = .174), previous outside experience (P = .611), or number of gantry angles (P = .156) was discovered. No statistical correlation between plan score and monitor unit or years of experience was found.
  
  
  CONCLUSIONS
  Despite clear and established critical organ dose criteria and well-documented planning guidelines, planning variation still occurs, even among members of the same institution. Because plan consistency does not seem to significantly correlate with experience, career path, or campus, investigation into alternate methods beyond additional education and training to reduce this variation, such as knowledge-based planning or advanced optimization techniques, is necessary.
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York. Electronic address: BerryS@MSKCC.org.
authors.forename: Sean L
authors.initials: SL
authors.lastname: Berry
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors.forename: Amanda
authors.initials: A
authors.lastname: Boczkowski
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors.forename: Rongtao
authors.initials: R
authors.lastname: Ma
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors.forename: James
authors.initials: J
authors.lastname: Mechalakos
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors.forename: Margie
authors.initials: M
authors.lastname: Hunt
mesh_terms: D018288:Carcinoma, Small Cell / Q000532:radiotherapy*; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D006282:Health Personnel; D006283:Health Physics; D006801:Humans; D008297:Male; D015588:Observer Variation; D058958:Organs at Risk; D010347:Patient Care Planning; D011874:Radiometry; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed