Creating method of cone beam CT (Captive Test) iterative reconstruction algorithm projection matrix

An iterative reconstruction algorithm and projection matrix technology, which is applied in the field of projection matrix construction of cone beam CT iterative reconstruction algorithm, can solve the problems of single image, easy to cause artifacts, low signal-to-noise ratio, etc.

Active Publication Date: 2012-11-14
THE PLA INFORMATION ENG UNIV
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Problems solved by technology

[0021] Although the research on CT iterative reconstruction projection matrix characterization model has achieved the above results, as the advantages of iterative reconstruction in low-dose, low signal-to-noise ratio, and incomplete data imaging and other application fields are further exerted, the reconstruction quality and model characterization accuracy Higher and higher requirements are also put forward. The current models are all models constructed based on geometric relationships or interpolation models. The description of the factors affecting the projection matrix is ​​relatively simple, which is easy to cause artifacts

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  • Creating method of cone beam CT (Captive Test) iterative reconstruction algorithm projection matrix
  • Creating method of cone beam CT (Captive Test) iterative reconstruction algorithm projection matrix
  • Creating method of cone beam CT (Captive Test) iterative reconstruction algorithm projection matrix

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Embodiment 1

[0077] The "Cone Beam CT Iterative Reconstruction Algorithm Projection Matrix Construction Method" of the present invention combines the respective characteristics of the ray coverage model and the basis function model, starts from the mathematical description of a continuous three-dimensional natural image, and fully considers the projection process according to the ray projection law. Mathematical characterization, a new projection matrix model is proposed, and the projection matrix construction method includes the following steps:

[0078] 1) Characterization of the reconstructed image by the 3D finite element model

[0079] A three-dimensional finite element model is introduced into the description of the reconstructed image, and the continuous reconstructed image (density distribution value) is set as in is the coordinate (x, y, z) of the spatial point, divides the reconstructed image area into J=N×N×N small cubes, and defines the local basis function in the jth small c...

Embodiment 2

[0094] The method for constructing the projection matrix of the cone-beam CT iterative reconstruction algorithm of this embodiment is different from that of Embodiment 1 in that: the ray coverage parameter Reflects the extent to which rays cover a voxel cube, which can be abstracted into points, lines or surfaces. If the length of the ray coverage voxel cube is used, the length model, the line integral of the ray coverage coefficient is the length of the i-th ray passing through the j-th voxel cube, using represents the slope-intercept equation of the i-th ray, then the parameter for,

[0095] s i ( r → ) = δ ( k → i · r → - τ i ...

Embodiment 3

[0097] The cone beam CT iterative reconstruction algorithm projection matrix construction method of this embodiment is different from the first or second embodiment in that: the basis function reflects the inhomogeneity inside the voxel cube, and the functions that can be used include Joseph method, Siddon method, Koehler method, Gaussian basis function, bicubic spline basis function and Kaiser-Bessel function, etc. Such as the Kaiser-Bessel function as the basis function , it is a spherical function in three-dimensional space, defined as:

[0098] b m , a , α ( r b , j ) = I m [ ...

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Abstract

The invention relates to a cone beam CT (Captive Test) iterative reconstruction algorithm and especially relates to a creating method of cone beam CT iterative reconstruction algorithm projection matrix. The invention provides a projection matrix characterization method based on a finite element model and a Radon operator for the high-precision characterization problem of the cone beam CT iterative reconstruction algorithm projection matrix. The invention provides a new projection matrix characterization method by combining the respective characteristics of a ray coverage model and a basis function model and fully considering the mathematic characterization of various physical processes of the projection according to the ray projection rule beginning from the mathematic characterization of a continuous three-dimensional natural image, so that the projection process is fully characterized. As shown in a test result, the method disclosed by the invention effectively improves the characterization precision and reconstruction quality of the model.

Description

technical field [0001] The invention relates to a cone-beam CT iterative reconstruction algorithm, in particular to a method for constructing a projection matrix of the cone-beam CT iterative reconstruction algorithm. Background technique [0002] With the wide application of computerized tomography (CT) in medical, industrial and security fields, the research on CT reconstruction algorithm has become one of the hot issues. CT reconstruction algorithms can be divided into two types in mathematics: Analytic Reconstruction (AR) and Iterative Reconstruction (IR). The advantage of the iterative reconstruction algorithm over the analytical reconstruction algorithm is that it can obtain better imaging quality under the condition of missing data or low signal-to-noise ratio. practical significance. The projection matrix of the iterative reconstruction algorithm is directly related to the known projection image and the reconstructed image to be obtained, and its characterization a...

Claims

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Application Information

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IPC IPC(8): G06T11/00
Inventor 李磊王超闫镔王林元张峰韩玉胡建伟
Owner THE PLA INFORMATION ENG UNIV
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