title: Limited benefit of inversely optimised intensity modulation in breast conserving radiotherapy with simultaneously integrated boost.
abstract: OBJECTIVE
  To examine whether in breast-conserving radiotherapy (RT) with simultaneously integrated boost (SIB), application of inversely planned intensity-modulated radiotherapy (IMRT-SIB) instead of three-dimensional RT (3D-CRT-SIB) has benefits that justify the additional costs, and to evaluate whether a potential benefit of IMRT-SIB depends on specific patient characteristics.
  
  
  METHODS
  3D-CRT-SIB and various IMRT-SIB treatment plans were constructed and optimised for 30 patients with early stage left-sided breast cancer. Coverage of planning target volumes (PTVs) and dose delivered to organs at risk (OARs) were determined for each plan. Overlap between heart and breast PTV (OHB), size of breast and boost PTVs and boost location were examined in their ability to identify patients that might benefit from IMRT-SIB.
  
  
  RESULTS
  All plans had adequate PTV coverage. IMRT-SIB generally reduced dose levels delivered to heart, lungs, and normal breast tissue relative to 3D-CRT-SIB. However, IMRT-SIB benefit differed per patient. For many patients, comparable results were obtained with 3D-CRT-SIB, while patients with OHB>1.4 cm and a relatively large boost PTV volume (>125 cm(3)) gained most from the use of IMRT-SIB.
  
  
  CONCLUSIONS
  In breast-conserving RT, results obtained with 3D-CRT-SIB and IMRT-SIB are generally comparable. Patient characteristics could be used to identify patients that are most likely to benefit from IMRT-SIB.
authors.affiliation: Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, The Netherlands. h.p.van.der.laan@rt.umcg.nl
authors.forename: Hans Paul
authors.initials: HP
authors.lastname: van der Laan
authors.forename: Wil V
authors.initials: WV
authors.lastname: Dolsma
authors.forename: Cornelis
authors.initials: C
authors.lastname: Schilstra
authors.forename: Erik W
authors.initials: EW
authors.lastname: Korevaar
authors.forename: Geertruida H
authors.initials: GH
authors.lastname: de Bock
authors.forename: John H
authors.initials: JH
authors.lastname: Maduro
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Langendijk
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated