Because x-rays can penetrate almost any object and yield information of the interior of specimens opaque to visible light,
they have been used as a powerful tool for the investigation of all kinds of materials and bodies right from their
discovery by Conrad Roentgen1 in 1895. Among the multitude of different ways such studies can be performed the
imaging methods play a predominant and most important role. The intent is to describe some interesting and relevant
ways x-ray imaging has been employed up to now. Clinical tomography will be excluded here. Recent surveys exist in
the literature, e.g.2.