Cone-beam CT from width-truncated projections

In this paper we report cone-beam CT techniques that permit reconstruction from width-truncated projections. These techniques are variants of Feldkamp's filtered backprojection algorithm and assume quasi-redundancy of ray integrals. Two methods are derived and compared. The first method involves the use of pre-convolution weighting of the truncated data. The second technique performs post-convolution weighting preceded by non-zero estimation of the missing information. The algorithms were tested using the three-dimensional Shepp-Logan head phantom. The results indicate that given an appropriate amount of overscan, satisfactory reconstruction can be achieved. These techniques can be used to solve the problem of undersized detectors. Copyright (C) 1996 Elsevier Science Ltd