title: Dose Distribution in the Heart and Cardiac Chambers Following 4-field Radiation Therapy of Breast Cancer: a Retrospective Study.
abstract: OBJECTIVE
  To evaluate cardiac doses in breast cancer patients with stage II/III treated with 4-field radiotherapy based on computed tomography (CT) dose planning.
  
  
  METHODS
  Based on archived CT images, whole heart and cardiac chamber radiation doses were analyzed in 216 (111 left-sided and 105 right-sided) mastectomized or lumpectomized breast cancer patients treated at a single institution, the Norwegian Radium Hospital, between 2000-2002. Individual dose volume histograms for the whole heart and for the four cardiac chambers were obtained, and mean, median and maximum doses to these structures were calculated. The dose (Gy) delivered to the 5% of the volume of each cardiac structure (D5%), and the volume percentage of each structure receiving ≥ 25 Gy (V25Gy) were reported. Normal tissue complication probability (NTCP) calculations were used to estimate the risk for ischemic heart disease (IHD).
  
  
  RESULTS
  Cohort-based medians of the whole heart mean dose (Dmean) for left- and right-sided tumors were 3.2 Gy and 1.3 Gy, respectively, with similar ventricular but lower atrial values. The atrial doses did not differ according to laterality of the breast tumor. In 13 patients with left-sided cancer, 5% of the heart volume was exposed to >25 Gy. The NTCP estimates were generelly low, with a maximum of 2.8%.
  
  
  CONCLUSIONS
  During adjuvant CT-based locoregional radiotherapy of women with breast cancer, the cardiac radiation doses are, at the group level, below recommended threshold values (D5% < 25 Gy), though individual patients with left-sided disease may exceed these limits.
authors.affiliation: Division of Cancer, Surgery and Transplantation, Department of Oncology, Oslo University Hospital, Radium Hospital, Oslo, Norway. ; Oslo and Akershus University College of Applied Sciences, Faculty of Health Sciences, Department of Radiotherapy/Radiography and Dental Tchnology, Oslo, Norway.
authors.forename: Safora
authors.initials: S
authors.lastname: Johansen
authors.forename: Kristin H
authors.initials: KH
authors.lastname: Tjessem
authors.forename: Kristian
authors.initials: K
authors.lastname: Fosså
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bosse
authors.forename: Turi
authors.initials: T
authors.lastname: Danielsen
authors.forename: Eirik
authors.initials: E
authors.lastname: Malinen
authors.forename: Sophie D
authors.initials: SD
authors.lastname: Fosså
keywords: breast cancer and radiation therapy; cardiac chambers; heart