title: Treatment of breast cancer with simultaneous integrated boost in hybrid plan technique : Influence of flattening filter-free beams.
abstract: OBJECTIVE
  The present study compares in silico treatment plans using hybrid plan technique during hypofractionated radiation of mammary carcinoma with simultaneous integrated boost (SIB). The influence of 6 MV photon radiation in flattening filter free (FFF) mode against the clinical standard flattening filter (FF) mode is to be examined.
  
  
  METHODS
  RT planning took place with FF and FFF radiation plans for 10 left-sided breast cancer patients. Hybrid plans were realised with two tangential IMRT fields and one VMAT field. The dose prescription was in line with the guidelines in the ARO-2010-01 study. The dosimetric verification took place with a manufacturer-independent measurement system.
  
  
  RESULTS
  Required dose prescriptions for the planning target volumes (PTV) were achieved for both groups. The average dose values of the ipsi- and contralateral lung and the heart did not differ significantly. The overall average incidental dose to the left anterior descending artery (LAD) of 8.24 ± 3.9 Gy in the FFF group and 9.05 ± 3.7 Gy in the FF group (p < 0.05) were found. The dosimetric verifications corresponded to the clinical requirements. FFF-based RT plans reduced the average treatment time by 17 s/fraction.
  
  
  CONCLUSIONS
  In comparison to the FF-based hybrid plan technique the FFF mode allows further reduction of the average LAD dose for comparable target volume coverage without adverse low-dose exposure of contralateral structures. The combination of hybrid plan technique and 6 MV photon radiation in the FFF mode is suitable for use with hypofractionated dose schemes. The increased dose rate allows a substantial reduction of treatment time and thus beneficial application of the deep inspiration breath hold technique.
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany. marzieh.bahrainy@radiologische-allianz.de.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Bahrainy
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kretschmer
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Vincent
authors.initials: V
authors.lastname: Jöst
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Kasch
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Würschmidt
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Dahle
authors.affiliation: Radiologische Allianz, Mörkenstrasse 47, 22767, Hamburg, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Lorenzen
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D000069473:Radiation Dose Hypofractionation; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D011882:Radiotherapy, High-Energy / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome
keywords: Breast cancer; Dose hypofractionation; Heart dose; Intensity-modulated radiotherapy; Volumetric-modulated arc therapy