Projection-space iterative interpolation for limited-angle tomography in parallel- and fan-beam geometry: Part 1

In computed tomography one reconstructs the image of an object from its projections. The limited-angle tomography problem arises when the number of projections available is too small, or the projections are not obtained from all angles around the object, evenly enough distributed. Such is the case, when the object moves while the projections are measured, for example CT - scanning the beating heart. A new algorithm, the projection-space iterative reconstruction-reprojection (PSIRR), estimates the missing projection data from the known data. This method is valid for parallel-beam projections only. In this paper their method is further modified and discussed. A similar iterative interpolation algorithm is derived for estimating missing projection data in fan-beam geometry. 10 refs., 5 figs.