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@INPROCEEDINGS{Gawai:841524,
      author       = {Gawai, Anugrah and Pomplun, Ekkehard and Kriehuber, Ralf},
      title        = {{STUDY} {ON} {CYTO}- {AND} {GENOTOXIC} {EFFECTS} {OF} {THE}
                      {AUGER} {ELECTRON} {EMITTER} {TECHNETIUM}-99{M} {IN}
                      {FUNCTIONAL} {RAT} {THYROID} {CELLS}},
      reportid     = {FZJ-2017-08568},
      year         = {2013},
      abstract     = {Introduction: Because of its favorable half-life (6.02
                      hours) and distinct characteristic gamma-line,
                      Technetium-99m (99mTc) is the most widespread radionuclide
                      in nuclear medicine. Additionally, this nuclide emits low
                      energetic, short-range Auger electrons which can deposit
                      relatively high energy in a rather small volume in the
                      immediate vicinity of the decay site. When located in close
                      proximity to the DNA, the biological effects caused by Auger
                      emitters are severe and assumed to be comparable with alpha
                      particles. This poses the question towards an enhanced
                      relative biological effectiveness (RBE) of Auger electron
                      emitter. To assess the potential impact of
                      99mTc-Pertechnetate on cellular level, the cyto- and
                      genotoxicity of 99mTc was investigated after extracellular
                      and intracellular localization in the functional rat thyroid
                      cell line, FRTL-5.Methods: FRTL-5 cells were exposed to
                      99mTc-pertechnetate (25, 50 and 75 MBq), either intra- or
                      extracellular located and colony-forming assay and
                      micronucleus (MN) assay was performed to assess cell killing
                      respectively micronucleus formation. For comparison FRTL-5
                      cells were externally irradiated with 137Cs (0.7 Gy/min). To
                      achieve extracellular localization of 99mTc, the
                      Sodium-Iodide Symporter (NIS) was inhibited with sodium
                      perchlorate (SP). The used amounts of activity and the
                      cellular uptake of 99mTc was measured and determined by
                      gamma-counting. The micro-dosimetric calculations were based
                      on cell size and Point-Kernel calculations using electron
                      spectra provided and published by Pomplun et al
                      (2006).Results: Rapid uptake of 99mTc by the FRTL-5 cells
                      was observed within the first few minutes after application.
                      The addition of SP restricted 99mTc from entering the
                      intracellular lumen by the NIS, however, no complete
                      inhibition of uptake was observed. 99mTc caused more
                      prominent cell killing and MN formation when located
                      intracellular as compared to extracellular localization per
                      decay. However, per dose unit no significant differences
                      were observed. Compared to high-dose rate external 137Cs
                      gamma-irradiation cell killing and MN formation was much
                      weaker after 99mTc-exposure as already published for MN
                      induction in SCL-II cells by Kriehuber et al. 2004. The SP
                      treatment itself had no influence on cyto- and genotoxic
                      damage.Conclusions: No significant effect of the
                      localization (intra- vs extracellular) of 99mTc on cell
                      killing and MN formation can be observed per unit dose
                      ruling out any “Auger effect” for 99mTc-pertechnetate.
                      Furthermore, the cytotoxic effect of 99mTc is much weaker
                      when compared to external high dose rate exposure (137Cs),
                      which is most likely to be explained by the low dose rate of
                      the 99mTc exposure.},
      month         = {Sep},
      date          = {2013-09-25},
      organization  = {16th Annual Meeting of the German
                       Society for Biological Radiation
                       Research, Darmstadt (Germany), 25 Sep
                       2013 - 27 Sep 2013},
      subtyp        = {After Call},
      cin          = {S-US},
      cid          = {I:(DE-Juel1)S-US-20090406},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/841524},
}