CT Scanner with improved processing efficiency 180 degrees fan angle reconstruction system

Year	Description
1993	Invention patented by Heang K. Tuy on November 31th, 1993. Abstract: An x-ray source (14) is rotated along a non-circular path (18) to irradiate a subject in an examination region (10) with a fan beam (16) of radiation. Radiation detectors convert rays of the fan beam which have traversed the examination region into electronic data which is stored as data fans in an initial data memory (22). Each data fan is zero-filled (24) and convolved by a convolver (30). Preferably, the convolver transforms each data fan into Fourier-space (32), filters each data fan in Fourier-space with a roll-off filter (36), and converts the filtered data fan back from Fourier-space (38). Each fan is weighted (42) by a 1/cos weighting function and stored in a weighted data memory (44). Rays which are redundant in a 180.degree.+ fan reconstruction are removed (46) from the convolved data fans. A pixel driven backprojector (50) backprojects each convolved and redundant ray removed data fan into an image memory (56). The backprojector weights each data value of each ray in proportion to 1/R, where R is a distance from the apex of the backprojected convolved fan to each corresponding pixel of the resultant image. A video processor (60) converts the electronic image representation stored in the image memory (56) into appropriate format for display on a video monitor (62).
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Invention: CT Scanner with improved processing efficiency 180 degrees+ fan angle reconstruction system