ABSTRACT
This chapter provides a short introduction to computed tomography (CT) and X-ray physics. CT is an advanced imaging technique that allows for non-invasive visualization of the interior of a scanned object. In CT, the three-dimensional attenuation distribution of the object that was imaged is reconstructed from a set of X-ray radiographs that were acquired from different angular viewpoints. To generate a proper photon flux in medical and lab-based CT systems, one has to work with polychromatic X-ray beams, consisting of photons within a continuous range of energies. The chapter explains that the number of detected X-ray quanta follow a Poisson distribution and describes a class of more stable statistical algorithms. Rigid sample motion, causing the projections to be misaligned, or affine deformation is a typical problem encountered in X-ray imaging. X-ray CT allows one to visualize the interior of objects by acquiring a set of radiographs and reconstructing an image from this set of measured projections.
