title: Flattening filter free technique in breath-hold treatments of left-sided breast cancer: The effect on beam-on time and dose distributions.
abstract: OBJECTIVE
  The use of flattening filter free (FFF) beams has potential to speed up deep-inspiration breath-hold treatments. In this study, the beam-on time and dose characteristics of left-sided breast treatment plans with FFF and flattened beams were evaluated.
  
  
  METHODS
  Twelve plans were generated for 20 patients. The techniques utilized were volumetric modulated arc therapy with two limited tangential arcs (tVMAT) and tangential intensity modulated radiotherapy with dynamic (dIMRT) as well as step-and-shoot (FinF) dose delivery. Each technique was planned with FFF and flattened beams with 6 and 10MV photons. All plans were irradiated and the beam-on times were measured. Dose characteristics of planning target volume (PTV) and organs at risk (OAR) were evaluated.
  
  
  RESULTS
  The mean beam-on times were reduced by 18-39% using FFF. Mean PTV dose coverage was least reduced with tVMAT (0.6-0.8%) compared to dIMRT (4%) and FinF (5.6-9.1%), when FFF beams were used instead of flattened beams. Only small differences were observed in OAR doses between equivalent plans (FFF vs. flattened).
  
  
  CONCLUSIONS
  A significant reduction was observed in beam-on time when utilizing FFF beams with tVMAT, dIMRT and FinF. tVMAT was the only technique for which the use of FFF did not degrade the treatment plan dose distributions.
authors.affiliation: Cancer Center, Kuopio University Hospital, Finland. Electronic address: tuomas.koivumaki@kuh.fi.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Koivumäki
authors.affiliation: Cancer Center, Kuopio University Hospital, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Heikkilä
authors.affiliation: Cancer Center, Kuopio University Hospital, Finland.
authors.forename: Anssi
authors.initials: A
authors.lastname: Väänänen
authors.affiliation: Cancer Center, Kuopio University Hospital, Finland.
authors.forename: Kristiina
authors.initials: K
authors.lastname: Koskela
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Finland.
authors.forename: Saara
authors.initials: S
authors.lastname: Sillanmäki
authors.affiliation: Cancer Center, Kuopio University Hospital, Finland.
authors.forename: Jan
authors.initials: J
authors.lastname: Seppälä
mesh_terms: D000368:Aged; D062485:Breath Holding; D005260:Female; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk; D017785:Photons; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D000069584:Unilateral Breast Neoplasms / Q000532:radiotherapy*
keywords: Breast cancer; Deep-inspiration breath-hold; Flattening filter free; Volumetric modulated arc therapy