title: Consistency in seroma contouring for partial breast radiotherapy: impact of guidelines.
abstract: OBJECTIVE
  Inconsistencies in contouring target structures can undermine the precision of conformal radiation therapy (RT) planning and compromise the validity of clinical trial results. This study evaluated the impact of guidelines on consistency in target volume contouring for partial breast RT planning.
  
  
  METHODS
  Guidelines for target volume definition for partial breast radiation therapy (PBRT) planning were developed by members of the steering committee for a pilot trial of PBRT using conformal external beam planning. In phase 1, delineation of the breast seroma in 5 early-stage breast cancer patients was independently performed by a "trained" cohort of four radiation oncologists who were provided with these guidelines and an "untrained" cohort of four radiation oncologists who contoured without guidelines. Using automated planning software, the seroma target volume (STV) was expanded into a clinical target volume (CTV) and planning target volume (PTV) for each oncologist. Means and standard deviations were calculated, and two-tailed t tests were used to assess differences between the "trained" and "untrained" cohorts. In phase 2, all eight radiation oncologists were provided with the same contouring guidelines, and were asked to delineate the seroma in five new cases. Data were again analyzed to evaluate consistency between the two cohorts.
  
  
  RESULTS
  The "untrained" cohort contoured larger seroma volumes and had larger CTVs and PTVs compared with the "trained" cohort in three of five cases. When seroma contouring was performed after review of contouring guidelines, the differences in the STVs, CTVs, and PTVs were no longer statistically significant.
  
  
  CONCLUSIONS
  Guidelines can improve consistency among radiation oncologists performing target volume delineation for PBRT planning.
authors.affiliation: Radiation Therapy Program, British Columbia (BC) Cancer Agency, Vancouver Island Centre, Victoria and Vancouver, BC, Canada.
authors.forename: Elaine K
authors.initials: EK
authors.lastname: Wong
authors.forename: Pauline T
authors.initials: PT
authors.lastname: Truong
authors.forename: Hosam A
authors.initials: HA
authors.lastname: Kader
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nichol
authors.forename: Lee
authors.initials: L
authors.lastname: Salter
authors.forename: Ross
authors.initials: R
authors.lastname: Petersen
authors.forename: Elaine S
authors.initials: ES
authors.lastname: Wai
authors.forename: Lorna
authors.initials: L
authors.lastname: Weir
authors.forename: Ivo A
authors.initials: IA
authors.lastname: Olivotto
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D006801:Humans; D017410:Practice Guidelines as Topic; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*; D020266:Radiotherapy, Conformal; D049291:Seroma / Q000000981:diagnostic imaging*