title: The relative biological effectiveness for carbon and oxygen ion beams using the raster-scanning technique in hepatocellular carcinoma cell lines.
abstract: BACKGROUND
  Aim of this study was to evaluate the relative biological effectiveness (RBE) of carbon (12C) and oxygen ion (16O)-irradiation applied in the raster-scanning technique at the Heidelberg Ion beam Therapy center (HIT) based on clonogenic survival in hepatocellular carcinoma cell lines compared to photon irradiation.
  
  
  METHODS
  Four human HCC lines Hep3B, PLC, HepG2 and HUH7 were irradiated with photons, 12C and 16O using a customized experimental setting at HIT for in-vitro trials. Cells were irradiated with increasing physical photon single doses of 0, 2, 4 and 6 Gy and heavy ion-single doses of 0, 0.125, 0.5, 1, 2, 3 Gy (12C and 16O). SOBP-penetration depth and extension was 35 mm +/-4 mm and 36 mm +/-5 mm for carbon ions and oxygen ions respectively. Mean energy level and mean linear energy transfer (LET) were 130 MeV/u and 112 keV/um for 12C, and 154 MeV/u and 146 keV/um for 16O. Clonogenic survival was computated and relative biological effectiveness (RBE) values were defined.
  
  
  RESULTS
  For all cell lines and both particle modalities α- and β-values were determined. As expected, α-values were significantly higher for 12C and 16O than for photons, reflecting a steeper decline of the initial slope of the survival curves for high-LET beams. RBE-values were in the range of 2.1-3.3 and 1.9-3.1 for 12C and 16O, respectively.
  
  
  CONCLUSIONS
  Both irradiation with 12C and 16O using the raster-scanning technique leads to an enhanced RBE in HCC cell lines. No relevant differences between achieved RBE-values for 12C and 16O were found. Results of this work will further influence biological-adapted treatment planning for HCC patients that will undergo particle therapy with 12C or 16O.
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany; Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Isma-ninger Str. 22, 81675, Munich, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Habermehl
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Katarina
authors.initials: K
authors.lastname: Ilicic
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Dehne
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rieken
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Orschiedt
authors.affiliation: Heidelberg Ion Beam Therapy Center (HIT), Im Neuenheimer Feld 450, 69120, Heidelberg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Brons
authors.affiliation: Heidelberg Ion Beam Therapy Center (HIT), Im Neuenheimer Feld 450, 69120, Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Haberer
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Klaus-Josef
authors.initials: KJ
authors.lastname: Weber
authors.affiliation: Department of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Isma-ninger Str. 22, 81675, Munich, Germany.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Combs
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D002244:Carbon / Q000627:therapeutic use; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000532:radiotherapy*; D056945:Hep G2 Cells; D006801:Humans; D007477:Ions / Q000627:therapeutic use; D018499:Linear Energy Transfer; D008113:Liver Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D010100:Oxygen / Q000627:therapeutic use; D017785:Photons / Q000627:therapeutic use; D012062:Relative Biological Effectiveness
chemical_list: D007477:Ions; D002244:Carbon; D010100:Oxygen