title: Inter-observer variation in delineating the coronary arteries as organs at risk.
abstract: To determine the inter-observer variation in delineating the coronary arteries as organs at risk (OAR) in breast cancer (BC) radiotherapy (RT) and how this variation affects the estimated coronary artery radiation dose.
  
  
  
  Delineation of the left main and the left anterior descending coronary artery (LMCA and LAD), and the right coronary artery (RCA), by using the heart atlas by Feng et al., was performed by three radiation oncologists in 32 women who had received adjuvant RT for BC. Centres of the arteries were calculated and distances between artery centres were measured and the artery radiation doses were estimated. The intraclass correlation coefficient (ICC) was used to quantify the variability in doses.
  
  
  
  Along the extent of RCA, the median distance between centres of arteries varied from 2 to 9mm with similar patterns over pairs of oncologists. For the LMCA-LAD the median distance varied from 1 to 4mm. The estimated maximum radiation doses showed an ICC variation from 0.82 to 0.97.
  
  
  
  The coronary arteries can be reliably identified and delineated as OARs in BC RT. The spatial variance is limited and the total variation in radiation dose is almost completely determined by the between patient variation.
authors.affiliation: Department of Surgical and Perioperative Science, Surgery, Umeå University, Sweden; Department of Oncology, Sundsvall Hospital, Sweden. Electronic address: anakinwen@gmail.com.
authors.forename: Anna-Karin
authors.initials: AK
authors.lastname: Wennstig
authors.affiliation: King's College London, Faculty of Life Sciences and Medicine, UK; Regional Cancer Centre, Uppsala, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Garmo
authors.affiliation: Department of Oncology, Gävle Hospital, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Hållström
authors.affiliation: Department of Immunology, Uppsala University, Sweden.
authors.forename: Petra Witt
authors.initials: PW
authors.lastname: Nyström
authors.affiliation: Department of Oncology, Gävle Hospital, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Edlund
authors.affiliation: Department of Oncology, Örebro University, Sweden.
authors.forename: Carl
authors.initials: C
authors.lastname: Blomqvist
authors.affiliation: Department of Surgical and Perioperative Science, Surgery, Umeå University, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Sund
authors.affiliation: Department of Oncology, Gävle Hospital, Sweden; Department of Immunology, Uppsala University, Sweden; Department of Oncology, Visby Hospital, Sweden.
authors.forename: Greger
authors.initials: G
authors.lastname: Nilsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000532:radiotherapy*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D058958:Organs at Risk / Q000000981:diagnostic imaging*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
keywords: Breast cancer radiotherapy; Coronary stenosis; Delineation; Inter-observer variation; Left anterior descending artery