Evaluation of different X-ray tube concepts with the simulation package ROSI

The modelling of complex X-ray tube setups requires a reliable simulation code which is also easy to use. ROSI (ROentgen Simulation, http://www.pi4.physik.uni- erlangen.de/Giersch/ROSI) was developed for that purpose and represents an object-oriented open source Monte Carlo simulation code that is based on the C++ library LSCAT-Gismo. The library uses the well established EGS4 code and its low energy extension LSCAT. We have worked on validating the simulation results by comparing them to measured spectra. The settings in the PEGS4 material files have been selected so that the approximations now fit best in the energy region that we work with. An X-ray tube example studied with ROSI was a Siemens angio tube. The geometries and materials were implemented in ROSI. The goal was to study the amount of backscattered electrons and their impact on the tubes mantle, as well as the amount of radiation that is produced by the electrons. Another example that was studied is the X-ray flux efficiency of a transmission tube design composed of a thin tungsten layer, compared to a conventional X-ray tube setup, e.g. a Siemens CT tube. Here different geometries, electron beam impact angles and material combinations were investigated in order to maximize the X-ray flux. The design was found to be indeed competitive and promises a factor two increase in the X-ray flux.