Software for X-ray fluorescence and scattering tomographic reconstruction

Computer tomography is commonly based on transmitted radiation, i.e. the part of the radiation that does not interact with the sample. In recent years the scientific community has demonstrated a growing interest in alternative tomographic techniques, based on fluorescence or on scattered radiation. These kinds of tomography provide complementary information about the sample, e.g., information concerning the spatial distribution of particular elements. Furthermore, they can be applied on experimental situations where a complete turn of the apparatus around the object is not possible. However, fluorescence tomography presents certain additional difficulties in comparison to transmission tomography. This is mainly due to self-absorption effects in the sample. Few algorithms for the correction of such effects are reported in the literature. The solution proposed by Hogan et al. provides a good compromise between image quality and reconstruction speed. In this paper we report an implementation of such an algorithm and also several examples. It is our intention that this paper and the included software represent the first part of a complete set of tools for scattering and fluorescence tomography, which we intend to present in the near future.