Patent ID: 6522714
Filing Date: 2003-02-18
Classification: A61B,G01T,G06T,Y10S

Abstract:
An apparatus for use with a CT imaging system including a radiation source and opposed detector mounted to a gantry on opposite sides of an imaging area, the detector including N separate detector rows arranged perpendicular to a translation axis, the apparatus for producing a tomographic slice image through a slice image plane passing through a region of interest (ROI) within an object from a projection data set acquired in a helical scan having a pitch p where the data set includes N separate row data sets corresponding to the N detector rows and each row data set correlates row views with gantry angles, a central angle &bgr; within the projection data set essentially aligned with the slice image plane, the apparatus comprising an image reconstructor configured to:create a separate projection data array for each of the N separate row data sets; apply a helical weighting function to each of the projection data arrays to generate a separate helical weighted array for each projection data array, the weighting function to be applied to each projection data array being: wr&af;(Î²,Î³)={0,Î²>Î²r31-Î²-Î²r2Î”&it;â€ƒ&it;Î²,Î²r1&GreaterEqual;Î²>Î²r21+Î²-Î²r2Î”&it;â€ƒ&it;Î²,Î²r2&GreaterEqual;Î²&GreaterEqual;Î²r10,Î²<Î²1&it;&NewLine;&it;where&it;â€ƒ&it;Î”&it;â€ƒ&it;Î²&it;â€ƒ&it;2&it;â€ƒ&it;Ï€p,â€ƒ&bgr;r1=tg&ggr;+r&Dgr;&bgr;, &bgr;2=&bgr;r1+&Dgr;&bgr;, and &bgr;r3=&bgr;r1+2&Dgr;&bgr;. â€ƒwhere tg is a tangent weighting parameter, &ggr; is a fan angle within each beam and r is the detector row number having a value between 0 and Nâˆ’1; and (c) construct a slice image using the helical weighted arrays.