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@INPROCEEDINGS{Gawei:839985,
author = {Gawei, Anugra and Pomplun, Ekkehard and Kriehuber, Ralf},
title = {{STUDY} {ON} {CYTOTOXIC} {EFFECTS} {OF} {AUGER} {ELECTRON}
{EMITTER} {TECHNETIUM}-99{M} {IN} {FUNCTIONAL} {RAT}
{THYROID} {CELLS}},
reportid = {FZJ-2017-07555},
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 cytotoxicity 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 clonogenic assay (colony-forming
assay, CFA) was performed to assess cell killing i.e. loss
of reproductive capacity. For comparison FRTL-5 cells were
externally irradiated with 137Cs (0.7 Gy/min; Gammacell-40).
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 as well as no elimination of
intracellular 99mTc by extensive washing steps before CFA
was observed, both much in contrast to reports of other
authors (Wendisch et al. 2012). 99mTc was able to cause more
prominent cell killing 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
the cell killing 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 cytotoxic damage.Conclusions: No significant
effect of the localization (intra- vs extracellular) of
99mTc on cell killing 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 = {2013-09-01},
organization = {40th Annual Meeting of the European
Radiation Research Society, Duplin
(Ireland), 1 Sep 2013 - 5 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/839985},
}