X ray source focus drifting CT reconstruction method

Abstract

The invention belongs to the field of X ray computerized tomography (CT) technology, in particular to an X ray source focus drifting CT reconstruction method. The method is based on the filtered backprojection reconstruction theory, deduces weighting, filtering and backprojection calculation formulas of ST projection data according to the CT scanning geometric construction during the focus drifting of an X ray source, introduces a distance parameter of the focus drifting of the X ray source during reconstruction, thereby forming a novel reconstruction algorithm. Since the CT scanning geometric construction corresponding to the traditional reconstruction algorithm is different from the structure formed during the focus drifting of the X ray source, the traditional reconstruction algorithm can not be used to reconstruct the image of a two-dimension CT projection the X ray source focus of which drifts. The invention solves the problem of X ray CT reconstruction under the condition of thefocus drifting of the X ray source and has a simple and highly-efficient reconstruction process.

Description

technical field [0001] The invention relates to an X-ray source focus drift CT reconstruction method, which belongs to the technical field of X-ray computerized tomography (CT). Background technique [0002] In the X-ray CT system, the X-ray source emits X-rays, which pass through a certain area of ​​the detected object from different angles, and the detector placed opposite the ray source receives them at corresponding angles, and then attenuates the rays according to different degrees at each angle. Using a certain reconstruction algorithm and computer calculations, the ray attenuation coefficient distribution mapping image of the scanned area of ​​​​the object is reconstructed, so that the image can be reconstructed by projection, and the characteristics of the medium density, composition, and structural shape of the object in the area can be reproduced without loss. . [0003] Modern CT systems generally use Filtered Back Projection (FBP) algorithms for image reconstruc...

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Problems solved by technology

[0005] In summary, although many scholars have analyzed the factors that cause the system to fail to meet the above conditions, such as detector deflection errors, rotation center errors, and geometric distance changes, and have derived corresponding image reconstruction formulas, no X-ray source has been studied. Focus drift, a factor that causes the system to fail to meet the above conditions, also does not propose a reconstruction method in this case

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