ABSTRACT
Water is a common surrogate of DNA for modelling the charged particle-induced ionizing processes in living tissue exposed to radiations. The present study aims at scrutinizing the validity of this approximation and then revealing new insights into proton-induced energy transfers by a comparative analysis between water and realistic biological medium. In this context, a self-consistent quantum mechanical modelling of the ionization and electron capture processes is reported within the continuum distorted wave-eikonal initial state framework for both isolated water molecules and DNA components impacted by proton beams. Their respective probability of occurrence-expressed in terms of total cross sections-as well as their energetic signature (potential and kinetic) are assessed in order to clearly emphasize the differences existing between realistic building blocks of living matter and the controverted water-medium surrogate. Consequences in radiobiology and radiotherapy will be discussed in particular in view of treatment planning refinement aiming at better radiotherapy strategies.
Subject(s)
DNA/chemistry , Protons , Radiobiology , Radiotherapy , Water/chemistry , Electrons , Energy Metabolism , Humans , KineticsABSTRACT
Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data.
Subject(s)
Electrons , Ions , Models, Theoretical , ProbabilityABSTRACT
In this work, we report total cross sections for the single electron capture process induced on DNA/RNA bases by high-energy protons. The calculations are performed within both the continuum distorted wave and the continuum distorted wave-eikonal initial state approximations. The biological targets are described within the framework of self-consistent methods based on the complete neglect of differential overlap model whose accuracy has first been checked for simpler bio-molecules such as water vapour. Furthermore, the multi-electronic problem investigated here is reduced to a mono-electronic one using a version of the independent electron approximation. Finally, the obtained theoretical predictions are confronted with the scarcely available experimental results.
