Backprojection for x-ray CT system
AssigneeGeneral Electric Company
InventorsFrancois Kotian, Gregg W. Martin, Stephen W. Metz, Arthur K. Collins, Michael A. Wu
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Abstract
An x-ray CT system acquires a series of views during a scan and reconstructs a slice image by backprojecting the filtered projection data from each acquired view. Backprojection is facilitated by employing a Cordic processor that produces the angle (.gamma.) and distance (L) of each pixel location from the x-ray source. The angle (.gamma.) selects the proper value from the filtered projection data, and this value is divided by the square of the distance (L) to arrive at a value used to update the slice image pixel value.
Claims5
A method for reconstructing an image from projection data acquired from a series of views taken through a slice, the steps comprising:
- a) acquiring x-ray projection data at one of said views through the slice;
- b) filtering the acquired view of x-ray projection data;
- c) backprojecting the view of filtered x-ray projection data to update the value of each of a plurality of pixels in a slice image by:
- i) applying information indicative of the location of one of said pixels to a Cordic processor which generates an angle (.gamma.) indicative of the location of an x-ray passing through the pixel location and a distance (L) indicative of the distance of the pixel location from an x-ray source;
- ii) calculating from the filtered x-ray projection data using the angle (.gamma.) a projection data value indicative of the x-rays passing through the pixel location;
- iii) dividing the projection data value by the square of the distance (L) and updating said one pixel value with the result;
- and
- iv) repeating steps (i), (ii) and (iii) until all of said pixel values have been updated;
- and
- d) repeating steps a), b) and c) until all of said views in the series have been acquired and backprojected.
Dependencies are inferred from the claim text.