A CT Image Reconstruction Method with Limited Sampling Angle

Abstract

The invention discloses a CT image reconstruction method under a limited range of sampling angles. The method comprises the following steps: (1) when the range of projection angles is smaller than 180 degrees, equal-angle-interval projection scanning is performed in a way of fan beam to obtain projection data Y; (2) a projection matrix A is calculated through an X ray source, a detector and position information of an object to be reconstructed; (3) a continuous image to be reconstructed is discretized by taking the center line of all projection directions as the horizontal axis and the direction vertical to the center line as the vertical axis; (4) a reconstruction model for the image reconstruction issue under a limited range of sampling angles is obtained according to the projection data Y and the projection matrix A and by considering the difference between the effects of gradients in different directions on image information restoration caused by the limited range of projection angles; and (5) the reconstruction model in the step (4) is solved to obtain a reconstructed image. By adopting the method of the invention, the impact of projection angle missing on reconstruction can be effectively reduced and a high-quality reconstructed image can be obtained under a limited range of sampling angles.

Description

technical field [0001] The invention relates to the field of internal image reconstruction of components in the precision electronic packaging process, in particular to a CT image reconstruction method with limited sampling angles. Background technique [0002] Computed Tomography (CT) is the product of the combination of X-ray photography and complex computer signal processing methods. On the premise of not destroying the structure of the object to be reconstructed, CT technology can accurately and intuitively reconstruct the internal structure of the object. At present, CT technology has been widely used in safety inspection, industrial non-destructive flaw detection and medical diagnosis and other fields. [0003] In the internal defect detection of packaged components, we need to reconstruct the internal image of components. In the process of X-ray projection of packaged components and acquisition of projection data, the components to be reconstructed are fixed on the ...

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Problems solved by technology

However, limited by the size and structure of the X-Ray equipment or the object to be reconstructed, the distance between the X-ray tube and the stage may be smaller than the rotation radius of the stage

Therefore, during the rotation process, the stage may collide with the closed X-ray tube, and cannot rotate 180 degrees. The projection data can only be obtained within the range of the projection angle less than 180 degrees, forming an image with a limited sampling angle. reconstruction problem

[0004] Aiming at the problem of image reconstruction under limited sampling angle, existing reconstruction methods such as Projection On Convex Sets-Total Variation (POCS-TV) algorithm do not consider the limited projection angle range in the reconstruction process In this case, high-quality reconstructed images cannot be obtained

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