title: Comments on ;A cone-beam filtered backprojection reconstruction algorithm for cardiac single photon emission computed tomography' by G. T. Gullberg and G. L. Zeng.
abstract: In the above-titled work by G. T. Gullberg and G. L. Zeng (ibid., vol.11, no.1, p.91-101, 1992), a fan-beam reconstruction formula of a noncircular scanning locus was derived and extended for half-scan cone-beam reconstruction. However, the reconstruction formula is not exact mathematically unless a necessary condition is satisfied. In this correspondence, the commenters derive this necessary condition and provide a geometrical explanation of the condition.
authors.affiliation: Dept. of Electr. & Comput. Eng., State Univ. of New York, Buffalo, NY.
authors.forename: G
authors.initials: G
authors.lastname: Wang
authors.forename: T H
authors.initials: TH
authors.lastname: Lin