A redundant ray projection completion method for an inverse fan beam computed tomography system

An actively synchronized heart gated computed tomography (CT) system has been developed at Peter Bent Brigham Hospital, Boston, MA, for a Technicare 2020 CT scanner. For even the most precise physical synchronization of the scanning apparatus, there will usually be a few gaps in the data for a particular time slice of the cardiac cycle. Of the several gap filling methods that have been developed here, the most nearly ideal is the use of redundant ray measurements. For this type of scanner, there are no truly redundant rays, and normalization errors are particularly problematic. A practical algorithm has been devised and tested here both on phantom data and on cardiac gated data (dog heart). The reconstructions obtained were usually artifact free and showed no loss of resolution, even when up to one-third of the projection data were replaced by redundant ray measurements.