title: Effect of high dose per pulse flattening filter-free beams on cancer cell survival.
abstract: OBJECTIVE
  To investigate if there is a statistically significant difference in cancer cell survival using a high dose per pulse flattening filter-free (FFF) beam compared to a standard flattened beam.
  
  
  METHODS
  To validate the radiobiological effect of the flattened and FFF beam, two glioblastoma cell lines were treated with either 5 or 10 Gy using different dose rates. Dose verification was performed and colony formation assays were carried out. To compare the predictability of our data, radiobiological models were included.
  
  
  RESULTS
  The results presented here demonstrate that irradiation of glioblastoma cell lines using the FFF beam is more efficient in reducing clonogenic cell survival than the standard flattened beam, an effect which becomes more significant the higher the single dose. Interestingly, in our experimental setting, the radiobiological effect of the FFF beam is dependent on dose per pulse rather than on delivery time. The used radiobiological models are able to describe the observed dose rate dependency between 6 and 24 Gy/min.
  
  
  CONCLUSIONS
  The results presented here show that dose per pulse might become a crucial factor which influences cancer cell survival. Using high dose rates, currently used radiobiological models as well as molecular mechanisms involved urgently need to be re-examined.
authors: Department of Radiation Oncology, University Hospital Zürich, Switzerland.
authors: Ines
authors: I
authors: Lohse
authors: Stephanie
authors: S
authors: Lang
authors: Jan
authors: J
authors: Hrbacek
authors: Stephan
authors: S
authors: Scheidegger
authors: Stephan
authors: S
authors: Bodis
authors: Nadia S
authors: NS
authors: Macedo
authors: Jianhua
authors: J
authors: Feng
authors: Urs M
authors: UM
authors: Lütolf
authors: Kathrin
authors: K
authors: Zaugg
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D004307:Dose-Response Relationship, Radiation; D005909:Glioblastoma / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D011829:Radiation Dosage; D011853:Radiobiology; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000295:instrumentation* / Q000379:methods*