Socpra Sciences Sante Et Humaines S.e.c.

Societe De Commercialisation Des Produits De La Recherche Appliquee Socpra Sciences Sante Et Humaines S.e.c.

Université De Sherbrooke

Jean-Daniel Leroux

Roger Lecomte

Marc Dumoulin

Réjean Fontaine

Rèjean Fontaine

Vitali Selivanov

An image reconstruction system and method based on image projection data collected by an imaging system having N tubes of response (TORs) having Naxial translation symmetries and Nin-plane rotation symmetries between the TORs. A system matrix mapping image projection data to pixels of an image is used, where the pixels are positioned according to a polar or cylindrical coordinate grid. During image reconstruction, matrix-vector computations are performed between the system matrix and vectors containing image estimates or image projection estimates. The matrix-vector computations are accelerated by structuring the system matrix coefficients, image vectors, and projection measurement vectors in such a way that symmetric data is stored in contiguous memory locations. Further, instead of storing the coefficients for all TOR and voxel combinations, matrix coefficients for only the subset of non-symmetric TOR and voxel combinations are stored, and the same coefficients are reused for the other symmetric TOR/voxel combinations.

Image reconstruction based on accelerated method using polar symmetries

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

Image reconstruction methods based on block circulant system matrices

Growing community of inventors

Sherbrooke, Canada

Jean-Daniel Leroux