title: A study of prostate delineation referenced against a gold standard created from the visible human data.
abstract: OBJECTIVE
  To measure inter- and intra-observer variation and systematic error in CT based prostate delineation, where individual delineations are referenced against a gold standard produced from photographic anatomical images from the Visible Human Project (VHP).
  
  
  METHODS
  The CT and anatomical images of the VHP male form the basic data set for this study. The gold standard was established based on 1mm thick anatomical photographic images. These were registered against the 3mm thick CT images that were used for target delineation. A total of 120 organ delineations were performed by six radiation oncologists.
  
  
  RESULTS
  The physician delineated prostate volume was on average 30% larger than the "true" prostate volume, but on average included only 84% of the gold standard volume. Our study found a systematic delineation error such that posterior portions of the prostate were always missed while anteriorly some normal tissue was always defined as target.
  
  
  CONCLUSIONS
  Our data suggest that radiation oncologists are more concerned with the unintentional inclusion of rectal tissue than they are in missing prostate volume. In contrast, they are likely to overextend the anterior boundary of the prostate to encompass normal tissue such as the bladder.
authors.affiliation: Department of Physics, Carleton University, Ottawa, Canada.
authors.forename: Zhanrong
authors.initials: Z
authors.lastname: Gao
authors.forename: David
authors.initials: D
authors.lastname: Wilkins
authors.forename: Libni
authors.initials: L
authors.lastname: Eapen
authors.forename: Christopher
authors.initials: C
authors.lastname: Morash
authors.forename: Youssef
authors.initials: Y
authors.lastname: Wassef
authors.forename: Lee
authors.initials: L
authors.lastname: Gerig
mesh_terms: D006801:Humans; D008297:Male; D009929:Organ Size; D011467:Prostate / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D014481:United States; D053443:Visible Human Projects