title: Evaluation of DNA damage induced by Auger electrons from137Cs.
abstract: To understand the biological effect of external and internal exposure from137Cs, DNA damage spectrum induced by directly emitted electrons (γ-rays, internal conversion electrons, Auger electrons) from137Cs was compared with that induced by137Cs γ-rays.
  
  
  
  Monte Carlo track simulation method was used to calculate the microscopic energy deposition pattern in liquid water. Simulation was performed for the two simple target systems in microscale. Radiation sources were placed inside for one system and outside for another system. To simulate the energy deposition by directly emitted electrons from137Cs placed inside the system, the multiple ejections of electrons after internal conversion were considered. In the target systems, induction process of DNA damage was modeled and simulated for both direct energy deposition and the water radical reaction on the DNA. The yield and spatial distribution of simple and complex DNA damage including strand breaks and base lesions were calculated for irradiation by electrons and γ-rays from137Cs.
  
  
  
  The simulation showed that the significant difference in DNA damage spectrum was not caused by directly ejected electrons and γ-rays from137Cs.
  
  
  
  The result supports the existing perception that the biological effects by internal and external exposure by137Cs are equivalent.
authors.affiliation: a Japan Atomic Energy Agency , Tokai , Ibaraki , Japan.
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Watanabe
authors.affiliation: a Japan Atomic Energy Agency , Tokai , Ibaraki , Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Hattori
authors.affiliation: a Japan Atomic Energy Agency , Tokai , Ibaraki , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kai
mesh_terms: D002588:Cesium Radioisotopes / Q000737:chemistry*; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D008956:Models, Chemical; D008957:Models, Genetic; D015233:Models, Statistical; D009010:Monte Carlo Method; D011829:Radiation Dosage; D012542:Scattering, Radiation
chemical_list: D002588:Cesium Radioisotopes; D004247:DNA
keywords: 137Cs; Auger electrons; DNA damage; Monte Carlo simulation; external exposure; internal exposure