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Method for correcting cone beam CT system geometric distortion based on symmetrically repetitive template

A geometric distortion and template technology, applied in computer tomography scanners, echo tomography and other directions, can solve the problem of complex template production

Active Publication Date: 2015-10-28
DALIAN UNIV OF TECH
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

Only single-angle projection data needs to be collected, the template is easy to make, and the measurement method is simple and effective, which solves the problems of collecting multi-angle projection data and complicated template making

Method used

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  • Method for correcting cone beam CT system geometric distortion based on symmetrically repetitive template
  • Method for correcting cone beam CT system geometric distortion based on symmetrically repetitive template
  • Method for correcting cone beam CT system geometric distortion based on symmetrically repetitive template

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Experimental program
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Effect test

Embodiment

[0087] The template used in the present invention is a 4×4 square grid.

[0088] Step 1: Obtain the angular deviation of the detector. The specific solution steps are as follows:

[0089] 1. Determine the original input image I and the initial value of the parameter τ. A rectangular area containing low-rank texture is selected as input in the collected projection image. Initialize the parameters, the initial values ​​of the angle parameters are θ=0, β=0, η=0, and the initialized parameters are expressed in the form of vectors as τ=[θ,β,η,t′ 1 , t' 2 ,t' 3 ], weight λ>0.

[0090] 2. Iterative loop: objective function value Global convergence is the condition for the end of the loop, and the specific steps are as follows:

[0091] 2.1. Calculate the Jacobian matrix ▽I of the image pair transformation τ:

[0092] I ( u i j ( ...

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Abstract

The invention relates to a method for correcting cone beam CT system geometric distortion based on a symmetrically repetitive template and belongs to the computed tomography technical field in the image processing field. According to the method provided by the invention, relations between angle deviation of a detector and the rank of a texture image; the solving of the angle deviation of the detector is equivalent to the minimization of the rank of the texture image under a certain constraint; the detector is adjusted according to the obtained angle deviation; and after the angle deviation is eliminated, and the displacement deviation of the detector is solved through utilizing a specific geometrical relationship. The low-rank texture-containing template is utilized to solved and obtained the angle deviation of a CT system, and it only needs to acquire a single-angle projection image; and the solving of the displacement deviation also only needs moving a rotary table for once, so that two projection images before and after change can be obtained. The method has the advantages of easiness in template manufacture as well as being simple and effective.

Description

technical field [0001] The invention belongs to the technical field of computer tomography (CT) in the field of image processing, and relates to a method for geometrically correcting a cone-beam CT imaging system by using a calibration template with symmetrical repetition. Background technique [0002] The geometric correction of computer tomography (Computed Tomography, CT) system is one of the basic problems to be solved in the field of CT research. As a new type of non-destructive testing equipment, industrial CT system is suitable for internal dimensions and Feature detection. In the industrial CT system, the ray source uses a cone beam ray source. In the cone beam CT imaging system, the center ray of the ray source is required to pass through the center of the plane of the detector perpendicular to the rotation axis, and the projection of the rotation axis falls on the center column of the detector. . However, in the installation and subsequent use of industrial CT sy...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B6/03
Inventor 孙怡郭立倩周丽平
Owner DALIAN UNIV OF TECH
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