title: Assessment of consistency in contouring of normal-tissue anatomic structures.
abstract: The purpose of this work is to estimate the uncertainty in the manual contouring of normal anatomical structures. The heart, esophagus, and spinal cord were contoured manually on six sets of computed tomography images by six dosimetrists whose experience ranged from 1 year to over 15 years. To determine the differences between inter- and intraobserver variations, each data set was contoured by one of the dosimetrists five times and once each by the five other dosimetrists. The magnitude of the discrepancies in delineating the contours was assessed. Intradosimetrist contouring discrepancies were as follows: esophagus, average 0.3 cm and maximum 2.9 cm; heart, average 0.5 cm and maximum 7.6 cm; and spinal cord, average 0.1 cm and maximum 0.7 cm. Interdosimetrist contouring discrepancies were as follows: esophagus, average 0.4 cm and maximum 3.1 cm; heart, average 0.7 cm and maximum 8.1 cm; and spinal cord, average 0.2 cm and maximum 0.9 cm. Significant discrepancies can occur when normal anatomic structures are contoured manually. Interdosimetrist discrepancies are typically slightly greater than intradosimetrist discrepancies. The magnitude of the discrepancies does not appear to be correlated to the experience of the dosimetrist.
authors.affiliation: Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA.
authors.forename: Dawn C
authors.initials: DC
authors.lastname: Collier
authors.forename: Stuart S C
authors.initials: SS
authors.lastname: Burnett
authors.forename: Mayankkumar
authors.initials: M
authors.lastname: Amin
authors.forename: Stephen
authors.initials: S
authors.lastname: Bilton
authors.forename: Christopher
authors.initials: C
authors.lastname: Brooks
authors.forename: Amanda
authors.initials: A
authors.lastname: Ryan
authors.forename: Dominique
authors.initials: D
authors.lastname: Roniger
authors.forename: Danny
authors.initials: D
authors.lastname: Tran
authors.forename: George
authors.initials: G
authors.lastname: Starkschall
mesh_terms: D004947:Esophagus / Q000033:anatomy & histology; D006321:Heart / Q000033:anatomy & histology; D006801:Humans; D008953:Models, Anatomic; D015588:Observer Variation; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D013116:Spinal Cord / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000706:statistics & numerical data*