Advanced tomography requires well-defined beams of the required type of radiation. This chapter discusses the generation of such beams and the fundamental interactions of these rays with solid matter. Topics covered include x-ray sources, and the generation of electrons and neutrons and their interaction with matter. It is shown that x-rays, neutrons, and electrons vary in the way they are produced as well as in the way they interact with matter. Each type of radiation has its own characteristics that determines the field of use of these rays for imaging. Electrons are most suitable for very small samples and very high resolutions, neutrons provide a tool for imaging thick samples at low resolutions. X-rays fill the intermediate range.
Keywords: advanced tomography, x-rays, electrons, neutrons, high resolutions