Wang G, Liu Y, Lin T H, Cheng P C
Division of Radiology Research, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110.
Scanning. 1994 Jul-Aug;16(4):216-20. doi: 10.1002/sca.4950160406.
An x-ray shadow projection microtomographic system using a scannable point source is under development at AMIL-ARTS, SUNY at Buffalo. To overcome the limitations of the commonly used Feldkamp's cone-beam reconstruction formula, we have developed a generalized Feldkamp-type cone-beam reconstruction formula. In the generalized Feldkamp-type cone-beam reconstruction, a scanning locus can be either planar or helix-like, and a transaxial slice is reconstructed using projection data collected from a 360 degrees angular range (full scan). In this paper, the full-scan cone-beam formula is modified to require only projection data of approximate 180 degrees plus two fan-angles (half scan). First, a half-scan derivative-free noncircular fan-beam reconstruction formula is formulated. Then, a half-scan cone-beam reconstruction formula is derived as an extension of the half-scan fan-beam reconstruction formula using Feldkamp's procedure. Typical numerical simulation results are given for both half-scan formulae. Compared with the full-scan cone-beam formula, the half-scan cone-beam formula reduces the involved angular range of projection data and allows better longitudinal/temporal resolution.
