The effect of ¹¹¹In radionuclide distance and auger electron energy on direct induction of DNA double-strand breaks: a Monte Carlo study using Geant4 toolkit

Abstract

Purpose: In this study, the effect of ¹¹¹In position and Auger electron energy on direct induction of DSBs was investigated.

Materials and methods: The Geant4-DNA simulation toolkit was applied using a simple B-DNA form extracted from PDBlib library. First, the simulation was performed for electrons with energies of ¹¹¹In and equal emission probabilities to find the most effective electron energies. Then, ¹¹¹In Auger electrons’ actual spectrum was considered and their contribution in DSB induction analysed.

Results: The results showed that the most effective electron energy is 183 eV, but due to the higher emission probability of 350 eV electrons, most of the DSBs were induced by the latter electrons. Also, it was observed that most of the DSBs are induced by electrons emitted within 4 nm of the central axis of the DNA and were mainly due to breaks with <4 base pairs distance in opposing strands. Whilst, when ¹¹¹In atoms are very close to the DNA, 1.3 DSBs have been obtained per decay of ¹¹¹In atoms.

Conclusions: The results show that the most effective Auger electrons are the 350 eV electrons from ¹¹¹In atoms with <4 nm distance from the central axis of the DNA which induce ∼1.3 DSBs per decay when bound to the DNA. This value seems reasonable when compared with the reported experimental data.

Keywords:

• Auger electrons
• double-strand breaks
• Indium-111
• targeted therapy
• Geant4-DNA

Acknowledgments

The authors would like to thank Dr. A. Moslehi, Ms. A. Zabihi and Dr. F. Semsarha for their constructive discussions. They are also grateful to Dr. Naser Zarsav for his precious contribution in improvement of this article.

Disclosure statement

No potential conflicts of interest was reported by the authors.

Additional information

Notes on contributors

Behnaz Piroozfar

Behnaz Piroozfar, B.Sc. and M.Sc. in nuclear physics, is a PhD student in nuclear engineering. Piroozfar has expertise in the field of health physics and radiation protection, and is proficient in computer codes applied in research: MCNP, Geant4.

Gholamreza Raisali

Gholamreza Raisali, B.Sc. and M.Sc. in nuclear physics, PhD in nuclear engineering, is a Professor of radiation physics. Raisali has expertise in the field of radiation dosimetry and radiation shielding, and is a specialist in Monte Carlo simulation. He is proficient in computer codes applied in radiation research: EGS4, MCNP, Geant4.

Behrouz Alirezapour

Behrouz Alirezapour, B.E. in laboratory sciences, M.S. in clinical biochemistry, PhD in clinical biochemistry, is a member of the academic staff at the Nuclear Science and Technology Research Institute (NSTRI). He has expertise in the field of radiolabeling of different types of monoclonal antibodies and peptides as well as QC and preclinical studies of radiolabeled agents.

Mohammad Mirzaii

Mohammad Mirzaii, B.Sc. in chemical engineering, M.Sc. in nuclear engineering, PhD in nuclear engineering, is an Associate Professor of radio isotope production. Mirzai has expertise in the field of cyclotron radioisotope production, and is a specialist in HPGe detector measurement. He is proficient in computer codes applied in research: ALICE, SRIM.