title: Beam angle manipulation to reduce cardiac dose during breast radiotherapy.
abstract: OBJECTIVE
  Standard tangential radiotherapy techniques after breast conservative surgery (BCS) often results in the irradiation of the tip of the left ventricle and the left anterior descending coronary artery (LAD), potentially increasing cardiovascular morbidity. The importance of minimising radiation dose to these structures has attracted increased interest in recent years. We tested a hypothesis that in some cases, by manipulating beam angles and accepting lower-than-prescribed doses of radiation in small parts of the breast distant from the surgical excision site, significant cardiac sparing can be achieved compared with more standard plans.
  
  
  METHODS
  A sample of 12 consecutive patients undergoing radiotherapy after left-sided BCS was studied. All patients were planned with a 6 MV tangential beam, beam angles were manipulated carefully and if necessary lower doses were given to small parts of the breast distant from the surgical excision site to minimise cardiac irradiation ("institutional" plan). Separate "hypothetical standard" plans were generated for seven patients using set field margins that met published guidelines.
  
  
  RESULTS
  In seven patients, the institutional plans resulted in lower doses to the LAD and myocardium than the hypothetical standard plans. In the other five patients, LAD and myocardial doses were deemed minimal using the hypothetical standard plan, which in these patients corresponded to the institutional plan (the patients were actually treated using the institutional plans).
  
  
  CONCLUSIONS
  Much attention has been devoted to ways of minimising cardiac radiation dose. This small sample demonstrates that careful manipulation of beam angles can often be a simple, but effective technique to achieve this.
authors.affiliation: Department of Clinical Oncology, Nottingham University Hospitals, Nottingham, UK. sinduvivek@doctors.org.uk
authors.forename: S
authors.initials: S
authors.lastname: Vivekanandan
authors.forename: J
authors.initials: J
authors.lastname: Mhlanga
authors.forename: D
authors.initials: D
authors.lastname: Launders
authors.forename: A
authors.initials: A
authors.lastname: Przeslak
authors.forename: D A L
authors.initials: DA
authors.lastname: Morgan
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D003331:Coronary Vessels / Q000528:radiation effects*; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D015412:Mastectomy, Segmental; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment