A comparative study of two postreconstruction beam hardening correction methods.

The general nature of postreconstruction beam hardening correction methods is discussed. A methodology for choosing the energy of reconstruction is presented based on a technique of evaluating the "nearness" of two projection data sets. Two previously published postreconstruction beam hardening correction methods are described within a common framework. These methods differ at a number of independent places and so one can produce hybrid methods by interchanging some but not all of the choices. A basic difference between the methods is that one needs only the initial reconstruction during the postreconstruction correcting phase, while the other needs the original projection data as well. Both methods have been implemented and are compared (using a mathematical head phantom) from the points of view of the nearness of the corrected polychromatic projection data to the desired monochromatic projection data and the visual quality of the reconstructions. Variants and hybrids of the two methods are also investigated and recommendations based on the results are presented.