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Projection center-of-rotation positioning method of computerized tomography (CT) system

A technology of rotation center and positioning method, which is applied in the field of radiation detection, can solve problems such as inability to deal with projection lateral truncation, and achieve strong practical value, simple and convenient operation, and easy-to-achieve effects

Active Publication Date: 2014-07-02
THE FIRST RES INST OF MIN OF PUBLIC SECURITY +1
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  • Claims
  • Application Information

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Problems solved by technology

This method has a high solution accuracy, but it cannot handle the case of projection transverse truncation

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  • Projection center-of-rotation positioning method of computerized tomography (CT) system
  • Projection center-of-rotation positioning method of computerized tomography (CT) system

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Embodiment Construction

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0026] Since the sinogram data obtained by 360-degree scanning of two-dimensional fan-beam CT is redundant, it is the main technical idea and principle of the method of the present invention to locate the projection rotation center coordinates using the redundancy of data information.

[0027] like figure 1 shown, where S m is the maximum projection address. According to the requirements of CT reconstruction on the projected coordinate system, the central beam passes through the rotation center of the turntable.

[0028] The relationship between the projections in the equiangular fan beam scanning process is as follows:

[0029] P(β,γ)=P(β+π-2γ,-γ) (1)

[0030] Among them, β is the rotation angle of the ray source, and γ is the projection (angle) address on the equiangular detector. P(β,γ), P(β+π-2γ,-γ) are called conjugate projections. Similar ...

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Abstract

The invention discloses a projection center-of-rotation positioning method of a computerized tomography (CT) system. The method comprises the steps of: acquiring 360-degree projection data to obtain a projection sinusoidal chart; setting a proper threshold, segmenting the projection sinusoidal chart, superposing and averaging the projection data of all projection angles according to corresponding pixels, i.e. superposing all lines of the projection sinusoidal chart and averaging to obtain one-dimensional signal y=f(s), using a quadratic polynomial y=as2+bs+c and adopting least square fitting y=f(s); and calculating horizontal coordinate values s=b / (-2a) of a symmetric center of a parabola y=as2+bs+c, wherein the horizontal coordinate values are the coordinate values of the projection center of rotation. The projection center-of-rotation positioning method of the CT system has the characteristics that the method is simple and convenient to operate, the noise interference is small, the accuracy is high, the realization is easy, the method is suitable for projection part cutoff and the practical value is greater.

Description

technical field [0001] The invention relates to a positioning method for a projection rotation center of a CT system, which belongs to the technical field of radiation detection. Background technique [0002] At present, for fan-beam ray scanning two-dimensional CT based on linear array detectors, the intersection of the line connecting the focus of the ray source and the center of rotation of the scanning table and the detector is the projection of the center of rotation of the scanning table on the detector, which is called the center of rotation of the projection. . The reconstruction algorithm commonly used in CT systems is the filtered back-projection algorithm. This algorithm requires the precise position of the projection rotation center on the detector to be known in advance. The error of the projection rotation center will cause ghosting in the reconstructed image and cause image distortion, which will affect Feature detection and recognition. For the actual CT sc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N23/04
Inventor 李保磊张耀军莫阳张萍宇
Owner THE FIRST RES INST OF MIN OF PUBLIC SECURITY