Pixel intensity distribution models for filtered back-projection

The authors define a pixel intensity distribution model (PIDM) to study the discretization of direct reconstruction schemes in a proper way. For the filtered backprojection (FBP) algorithm, this leads to a derivation of the filter for a B-spline PIDM and its discretization, a simple but exact implementation for this class of functions, and a rule for the sampling ratio relating pixel size to projection cell size according to the device characteristics. Actual phantom reconstructions are presented both for standard and spline FBP schemes. The degree of the B-spline reconstruction is discussed in connection with the angular sampling and the kind of detection task to be applied on the image.<>