title: Prostate contouring variation: can it be fixed?
abstract: OBJECTIVE
  To assess whether an education program on CT and MRI prostate anatomy would reduce inter- and intraobserver prostate contouring variation among experienced radiation oncologists.
  
  
  METHODS
  Three patient CT and MRI datasets were selected. Five radiation oncologists contoured the prostate for each patient on CT first, then MRI, and again between 2 and 4 weeks later. Three education sessions were then conducted. The same contouring process was then repeated with the same datasets and oncologists. The observer variation was assessed according to changes in the ratio of the encompassing volume to intersecting volume (volume ratio [VR]), across sets of target volumes.
  
  
  RESULTS
  For interobserver variation, there was a 15% reduction in mean VR with CT, from 2.74 to 2.33, and a 40% reduction in mean VR with MRI, from 2.38 to 1.41 after education. A similar trend was found for intraobserver variation, with a mean VR reduction for CT and MRI of 9% (from 1.51 to 1.38) and 16% (from 1.37 to 1.15), respectively.
  
  
  CONCLUSIONS
  A well-structured education program has reduced both inter- and intraobserver prostate contouring variations. The impact was greater on MRI than on CT. With the ongoing incorporation of new technologies into routine practice, education programs for target contouring should be incorporated as part of the continuing medical education of radiation oncologists.
authors.affiliation: Radiation Oncology Queensland, St Andrew's Cancer Care Center, St Andrew's Hospital, Toowoomba, Queensland, Australia. eric.khoo@roq.net.au
authors.forename: Eric L H
authors.initials: EL
authors.lastname: Khoo
authors.forename: Karlissa
authors.initials: K
authors.lastname: Schick
authors.forename: Ashley W
authors.initials: AW
authors.lastname: Plank
authors.forename: Michael
authors.initials: M
authors.lastname: Poulsen
authors.forename: Winnie W G
authors.initials: WW
authors.lastname: Wong
authors.forename: Mark
authors.initials: M
authors.lastname: Middleton
authors.forename: Jarad M
authors.initials: JM
authors.lastname: Martin
mesh_terms: D004502:Education, Medical, Continuing / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D018787:Radiation Oncology / Q000193:education*; D014057:Tomography, X-Ray Computed / Q000379:methods*