Nanodosimetric characterization of ion beams*
Physikalisch-Technische Bundesanstalt (PTB), Bundesallee
Received: 7 January 2014
Received in final form: 22 April 2014
Published online: 7 August 2014
The characterization of particle track structure is essential for an estimation of radiobiological effects, particularly in the case of densely ionizing radiation. The particle track structure can be characterized by nanodosimetric quantities which are measurable by means of a nanodosimeter. Results obtained from experiments with the nanodosimeter can be used to validate track structure simulations, which are essential for estimating track structure parameters in biological material. For this purpose, the dedicated Monte Carlo code PTra has been developed to simulate the nanodosimeter setup as well as nanometric targets consisting of water. Recently, electron-impact cross section data of DNA constituents measured at PTB were implemented into PTra. A calculation of nanodosimetric quantities in DNA-analog media shows considerable differences to results obtained in water medium, particularly for electron energies lower than 200 eV. These discrepancies become more considerable when nanodosimetric quantities are used to estimate biological effects. This paper aims to provide an overview of the present status of nanodosimetry, focusing on the experimental and simulation work at PTB. Furthermore, the suitability of simple models directly linking nanodosimetric track structure characteristics and radiobiological effectiveness is discussed.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014