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A quasiexact reconstruction algorithm for helical CT using a 3‐Pi acquisition
Author(s) -
Bontus Claas,
Köhler Thomas,
Proksa Roland
Publication year - 2003
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1601913
Subject(s) - algorithm , iterative reconstruction , reconstruction algorithm , data acquisition , radon , radon transform , filter (signal processing) , computer science , mathematics , computer vision , physics , quantum mechanics , operating system
Recently, an exact reconstruction method for helical CT was published by A. Katsevich. The algorithm is of the filtered backprojection type and is, therefore, computationally efficient. Moreover, during backprojection, only data are used which correspond to an illumination interval of 180° as seen from the object‐point. We propose a new reconstruction method, which is applicable to data obtained with a 3‐Pi acquisition [IEEE Trans. Med. Imaging 19 , 848–863 (2000)]. The method uses the same filter types as the Katsevich algorithm, but the directions and the number of the filter lines are chosen differently. For the derivation of the new algorithm, we analyze the relationship of the Katsevich method and radon inversion. A certain radon plane can intersect with the backprojection interval related to a 3‐Pi acquisition either once, three, or five times. In analogy to the definition of quasiexactness introduced by Kudo et al. for a 1‐Pi acquisition, we use the term quasiexactness for algorithms on a 3‐Pi acquisition, if radon planes with one or three intersections within the backprojection interval are treated correctly. Using the results on the relationship with radon inversion, we can prove that our algorithm is quasiexact in this sense. We use simulation results in order to demonstrate that the algorithm yields excellent image quality.