Calculation of DNA strand breaks due to direct and indirect effects of Auger electrons from incorporated 123I and 125I radionuclides using the Geant4 computer code.
OBJECTIVE
In this work the number of DNA single-strand breaks (SSB) and double-strand breaks (DSB) due to direct and indirect effects of Auger electrons from incorporated (123)I and (125)I have been calculated by using the Geant4-DNA toolkit. We have performed and compared the calculations for several cases: (125)I versus (123)I, source positions and direct versus indirect breaks to study the capability of the Geant4-DNA in calculations of DNA damage yields.


METHODS
Two different simple geometries of a 41 base pair of B-DNA have been simulated. The location of (123)I has been considered to be in (123)IdUrd and three different locations for (125)I.


RESULTS
The results showed that the simpler geometry is sufficient for direct break calculations while indirect damage yield is more sensitive to the helical shape of DNA. For (123)I Auger electrons, the average number of DSB due to the direct hits is almost twice the DSB due to the indirect hits. Furthermore, a comparison between the average number of SSB or DSB caused by Auger electrons of (125)I and (123)I in (125)IdUrd and (123)IdUrd shows that (125)I is 1.5 times more effective than (123)I per decay.


CONCLUSIONS
The results are in reasonable agreement with previous experimental and theoretical results which shows the applicability of the Geant-DNA toolkit in nanodosimetry calculations which benefits from the open-source accessibility with the advantage that the DNA models used in this work enable us to save the computational time. Also, the results showed that the simpler geometry is suitable for direct break calculations, while for the indirect damage yield, the more precise model is preferred.
Radiation Applications Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, Tehran. graisali@aeoi.org.ir
Gholamreza
G
Raisali
Lalageh
L
Mirzakhanian
Seyed Farhad
SF
Masoudi
Farid
F
Semsarha
D004247:DNA / Q000737:chemistry / Q000235:genetics; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D053904:DNA Breaks, Single-Stranded / Q000528:radiation effects*; D004583:Electrons; D007457:Iodine Radioisotopes; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012984:Software
D007457:Iodine Radioisotopes; D004247:DNA