Cone beam CT image reconstruction method

Abstract

The invention discloses a cone beam CT image reconstruction method, which comprises the following steps: S10, measuring projection images of water with different thicknesses under a preset ray dose, and obtaining a relation comparison table of pixel values and water thickness values according to the projection images; s20, under the same ray dose as the step S10, rotationally collecting projection images of the measured object at different angles; s30, finding out a corresponding water thickness value in the comparison table obtained in the step S10 according to the pixel value of the projection image obtained in the step S20, and forming an equivalent projection water thickness image; s40, reconstructing the equivalent projection water thickness image formed in the step S30 to obtain a three-dimensional matrix of the equivalent water thickness of each voxel of the measured object; s50, obtaining a three-dimensional matrix of the material coefficient according to the numerical relationship between the material coefficient and the water thickness value; and S60, calculating the CT value of each voxel of the measured object according to the three-dimensional matrix of the material coefficients obtained in the step S50, and obtaining a final cone beam CT image.

Description

technical field [0001] The invention relates to the technical field of medical imaging, in particular to a cone-beam CT image reconstruction method. Background technique [0002] Cone beam CT (CBCT), which has emerged in modern times, has been widely used in interventional therapy, oral digital imaging, and image-guided radiation therapy due to its advantages of compact structure and fast three-dimensional imaging. [0003] Such as figure 1 As shown, the cone beam CT device usually consists of a rotating frame, an X-ray source, and a detection board, wherein the X-ray source and the detection board are relatively installed on the rotating frame and rotate with the rotating frame. [0004] Cone beam CT uses multiple X-ray pulse exposures on the rotation trajectory to reconstruct three-dimensional images using projection data from multiple angles. Common reconstruction methods include: [0005] a. Filtered back projection method: Filtered back projection method is a kind of ...

AI Technical Summary

Problems solved by technology

Ideally, the CBCT value is accurate. However, in the actual imaging process, it is often affected by scattered rays and ray hardening. If no compensation is made, the reconstructed image will produce serious artifacts and seriously affect the image quality.

[0008] X-ray scattering is that when X-rays interact with matter, in addition to being absorbed by the matter, they may also be scattered by the matter. A large number of scattered signals reach the flat panel detector, which will cause a large amount of scattering noise in the CBCT projection image, and the reconstructed image will be have severe cupping artifacts

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