Reconstruction tomography from incomplete projections

The findings reported are equally applicable to the fields of radiology and nuclear medicine, but the data discussed was aquired with scintillation cameras. Incomplete projections are obtained when the field of view of the detector is limited or when an opaque object lies within the field of view. It is possible to carry out reconstructions from such projections by extimating the missing projection values. A preferable method in most instances, however, appears to be the additive ART iterative method, modified to ignore the missing projection values. When the field of view is limited, one can use knowledge of the true outline of the density or radioactivity distribution to obtain improved reconstructions, by trimming the margin of the reconstruction array at the beginning of, or during, iterative reconstruction. The modified additive ART method, utilizing such trimming, appears to be clearly superior to any other method for reconstruction from projections which cover a limited field of view