Reduction of hitlist size in spiral cone beam CT by use of local radon origins

摘要

A method and apparatus for reconstructing an image of an object using a three dimensional (3D) computerized tomographic (CT) imager having a cone beam radiation source and detector arrangement for acquiring measurement data. The source and detector arrangement is operated at a plurality of source positions along a spiral scan path so as to acquire a corresponding plurality of sets of measurement data representative of radiation attenuation caused by the object. Image reconstruction processing information required for processing of the acquired measurement data in a Radon space partitioned by plurality of vertically oriented coaxial phi -planes for reconstructing the image, is pre-calculated and stored in a hitlist. The stored information is pre-calculated on less that all of the phi -planes, but due to a symmetry that is induced in the reconstruction processing, the stored information can be used for calculating Radon data for all of the phi -planes that partition the Radon space. The size of the hitlist is thus reduced by a factor equal to the number of phi -planes for which the stored information is re-used, e.g., 360 for +E,fra 1/2+EE degree phi -plane spacing and storage of reconstruction processing information for a single phi -plane.