INCORPORATING A-PRIORI INFORMATION INTO THE SHEFFIELD FILTERED BACKPROJECTION ALGORITHM

The Sheffield image reconstruction algorithm is based on the assumptio n that the initial conductivity distribution of the body being imaged is uniform. In many situations this assumption is violated. Previous a ttempts at incorporating a priori information by modifications to the backprojection matrices were ineffective. An alternative method of inc luding a priori information became apparent following the recent refor mulation of the Sheffield image reconstruction algorithm. Applying mat rix algebra to the image reconstruction equations reveals that the inc orporation of a priori information can be considered as either a modif ication to the original backprojection matrix or a component of a comp osite data filter. A simple two-dimensional model of the adult head wa s chosen to test this approach. The results of imaging studies using s ynthetic data derived from this model show that a priori information h as been successfully incorporated into the image reconstruction proces s. The ability to include a priori information into the image reconstr uction process may have significant implications for the more challeng ing applications of Err such as imaging the adult head.