title: Does breast size affect the scatter dose to the ipsilateral lung, heart, or contralateral breast in primary breast irradiation using intensity-modulated radiation therapy (IMRT)?
abstract: OBJECTIVE
  To evaluate the relationship between the primary breast volume and dose received by the ipsilateral lung, heart (for left-breast cancers), and contralateral breast during primary breast irradiation using intensity-modulated radiation therapy (IMRT).
  
  
  METHODS
  Sixty-five patients with breast carcinoma were treated using 6-MV photons with IMRT technique using the Eclipse Planning System following breast conserving surgery. All patients had a treatment planning CT scan. The primary breast, ipsilateral lung, and heart were contoured on the axial CT slices. The primary breast volume was calculated using the Eclipse Planning System. The mean ipsilateral lung and heart doses were obtained from the dose-volume histogram. The contralateral breast dose was measured using paired thermoluminescent dosimeters (TLDs) placed on the patient's contralateral breast, 4 cm from the center of the medial border of the primary breast irradiation field.
  
  
  RESULTS
  The mean dose delivered with photons to the primary breast for all patients was 49.97 Gy. The mean volume of the primary irradiated breast was 1167.9 cc. As a percentage, the mean ipsilateral lung, heart, and contralateral breast doses were 11.2%, 6.1%, and 7.2%, respectively. The primary breast volume positively correlated with the contralateral breast dose (P < 0.0005). There was no significant correlation between the breast volume and the ipsilateral lung or heart dose (P = 0.463 and 0.943, respectively).
  
  
  CONCLUSIONS
  This study suggests that the primary breast size significantly affects the scatter dose to the contralateral breast but not the ipsilateral lung or heart dose when using IMRT for breast irradiation.
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, USA.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Bhatnagar
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Heron
authors.forename: Melvin
authors.initials: M
authors.lastname: Deutsch
authors.forename: Edward
authors.initials: E
authors.lastname: Brandner
authors.forename: Andrew
authors.initials: A
authors.lastname: Wu
authors.forename: Shalom
authors.initials: S
authors.lastname: Kalnicki
mesh_terms: D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D002277:Carcinoma / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D007839:Functional Laterality; D006321:Heart / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000528:radiation effects; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D017785:Photons / Q000627:therapeutic use; D014057:Tomography, X-Ray Computed