General considerations
X-ray medical imaging. 3D image processing

An X-ray radiograph is the projection (to use the CT term) onto a plane (a detector) of a part of the human body. If we disregard scattered radiation, each pixel of the detector receives attenuated radiation, and this attenuation is the sum of the attenuations of each infinitesimal volume that the radiation has passed through since the source, assimilating the body passed through to a three-dimensional tiling of infinitesimal volumes of homogeneous attenuation (figure