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Comparison of different approaches to investigate radiation damage at nanometer level

02.01.2012

In an ongoing study, performed in collaboration with the Frankfurt Institute for Advanced Studies (FIAS), different methodologies to assess direct radiation damage to the DNA by passing ions with an energy of the Bragg peak are compared. The goal of this work is to investigate to what extent the results of a detailed Monte Carlo track structure simulation developed at PTB (PTra) [1,2] can be reproduced by an analytical method, which was developed at FIAS [3].

To this date, the comparison was carried out for the radial dependence of the expectation values of the deposited energy per volume ("radial dose") of 10 MeV alpha particles in nitrogen as well as of the electron flux through the surface of a cylindrical target (equal in size to a short DNA segment and filled with water) caused by a passing 0.3 MeV/u C-ion (Figure). The results of both methods showed good agreement. In the ongoing collaboration, further parameters such as the radial dose distribution and the ionization cluster size obtained in a nanometric water cylinder as function of radial distance to a 0.3 MeV/u C-ion track will also be compared.

In addition, the ionization cluster size distribution produced by alpha particles of energies between 0.592 MeV to 10 MeV in the PTB/WIS nanodosimeter filled with nitrogen of 120 Pa pressure will be calculated by both approaches to compare the results also to measured data.

Figure : Flux N through the surface of a cylinder of 2.3 nm diameter and 3.4 nm length as function of the radial distance ρ to the 0.3 MeV/u C-ion track in water. The solid line shows the results from the analytical approach, the dots those from the track structure simulation.

Literature

  1. B. Grosswendt and S. Pszona:
    The track structure of α-particles from the point of view of ionization-cluster formation in "nanometric" volumes of nitrogen.
    Radiat. Environ. Biophys. 41, 91-102 (2002).
  2. B. Grosswendt:
    Formation of ionization clusters in nanometric structures of propane-based tissue-equivalent gas or liquid water by electrons and α-particles.
    Radiat. Environ. Biophys. 41, 103-112 (2002).
  3. A. V. Solov’yov, E. Surdutovich, E. Scifoni, I. Mishustin, W. Greiner:
    Physics of ions beam cancer therapy: a multiscale approach.
    Phys. Rev. E 79, 011909 (2009).