title: Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.
abstract: OBJECTIVE
  In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery.
  
  
  METHODS
  The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity.
  
  
  RESULTS
  The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation.
  
  
  CONCLUSIONS
  The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.
authors.affiliation: a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Beyreuther
authors.affiliation: b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Karsch
authors.affiliation: a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.|b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Lydia
authors.initials: L
authors.lastname: Laschinsky
authors.affiliation: a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Leßmann
authors.affiliation: b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Naumburger
authors.affiliation: b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Oppelt
authors.affiliation: a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.|b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.|c Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.|d German Cancer Consortium (DKTK), Dresden, Germany and German Cancer Research Center (DKFZ) , Heidelberg , Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Richter
authors.affiliation: b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schürer
authors.affiliation: b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Woithe
authors.affiliation: a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.|b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Pawelke
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000503:physiopathology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D006801:Humans; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000528:radiation effects
keywords: Pulsed electron treatment; in vitro dose response; laser particle acceleration; ultra-high pulse dose rate