Pre-calculated hitlist for reducing run-time processing of an exact cone beam reconstruction algorithm

A method of operating a 3D CT imaging apparatus having a cone beam radiation source and detector arrangement, for reconstructing an image of an object that is scanned by said source and detector arrangement, comprising the following steps:

• before the acquisition of measurement data during an imaging operation of the apparatus,
• pre-calculating and storing image reconstruction processing information required for processing of the acquired measurement data to develop contributions to the final reconstruction of the image, which information is stored in an organized format that indicates the correspondence between sample points in Radon space and the source positions that develop measurement data that can be processed to contribute numerical values thereto;
• and
• during the imaging operation of the apparatus, operating said source and detector arrangement at a plurality of source positions along a scan path so as to acquire a corresponding plurality of sets of said measurement data, and
• processing the acquired measurement data using said pre-calculated image reconstruction processing information for developing said contributions and reconstructing the image.

A scanning and data acquisition apparatus for three dimensional (3D) computerized tomography (CT) imaging of an object in a field of view radially centered on a predetermined axis, comprising:

• an energy source (10) for emitting energy in the form of a cone beam;
• an area detector (12) for detecting as measurement data cone beam energy after attenuation by passage through an object to be imaged;
• a manipulator (6) for movably positioning said source and detector along a scan path relative to the object, to cause irradiation of said object by said source at multiple source positions along said scan path about said object, said detector acquiring a corresponding set of measurement data at each said source position;
• control means (8) for defining the scan path as a plurality of spaced stages on a predetermined geometric surface surrounding the field of view, with each of a plurality of planes that pass through the field of view and intersect the scan path in at least one point as well as the area detector, being useful for calculating Radon data at a given one of a plurality of Radon sample points;
• image reconstruction processing means (18) including means for calculating Radon data for each of said Radon sample points by processing multiple ones of the sets of measurement data, for developing image data;
• and
• display means (28) responsive to said image data for displaying a reconstructed image of the object;
• wherein said image reconstruction processing means (18) includes a database (21) of reconstruction processing information that is dependant on the geometric parameters of the imager, which information is precalculated and stored before acquisition of the measurement data, and then used by said image reconstruction processing means (18) during imaging operation of said apparatus for facilitating processing of the measurement data to calculate the Radon data.