Proc. Inter. Symp. Med. Imag. and Imag. Interp., pp. 527-533 (IEEE, 1982)

Limited angle CT reconstruction using a priori information

Kenneth M. Hanson
Los Alamos National Laboratory


Projection data that are limited in number and range of viewing angle cannot completely specify an arbitrary source function, In the space of all permissible functions there exists a null subspace about which the projection measurements provide no information. Deterministic reconstruction algorithms usually set the null space contributions to zero, leading to severe reconstruction artifacts. A Fit And Iterative Reconstruction (FAIR) method is proposed that incorporates a priori knowledge of the approximate functional form of the source, In FAIR the parameters of this functional model are determined from the available projection data by a weighted fitting procedure. The resulting distribution is then iteratively revised to bring the final estimate into agreement with the measured projections using a standard algorithm such as ART.

Keywords: incomplete data, missing data, null space, artifacts, algebraic reconstruction technique (ART), nonnegativity constraint, prior knowledge

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