Geometrical parameter calibration method of X-ray cone beam computed tomography system

A technology of geometric parameters and tomography, used in echo tomography, material analysis using radiation, computer tomography scanners, etc., can solve problems such as complex calibration process

Active Publication Date: 2012-10-24
TSINGHUA UNIV
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  • Application Information

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Problems solved by technology

At the same time, the current calibration method is to calibrate and adjust each geometric parameter one by one. Due to the correlation between parameters, it often needs to be adjusted repeatedly one by one, which makes the calibration process very complicated.

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  • Geometrical parameter calibration method of X-ray cone beam computed tomography system
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  • Geometrical parameter calibration method of X-ray cone beam computed tomography system

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Embodiment Construction

[0130] Technical solutions:

[0131] 1) Establishment of cone beam CT system model

[0132] A typical cone beam CT system includes three parts: X-ray source, flat panel detector and rotation system. During CT reconstruction, the geometric relationship between the three parts is used to reconstruct the density of the detected object or the spatial distribution of the X-ray attenuation coefficient according to multiple projection data. The traditional calibration method is to consider the geometric parameters and errors of the system one by one, and measure and adjust them one by one to make the installation error close to zero and obtain accurate imaging geometric parameters. like figure 1 As shown, the coordinate system of the system is defined with the platform plane of the system as the reference system. The ideal geometric condition is: the line connecting the X-ray source and the center of the flat panel detector passes through the coordinate origin and falls on the plat...

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Abstract

The invention discloses a geometrical parameter calibration method of an X-ray cone beam computed tomography system and belongs to the field of the X-ray cone beam computed tomography systems (a cone beam CT for short). By means of a camera calibration technique, a geometrical position relationship among an X-ray source, a panel detector and a rotary shaft in a cone beam CT system is reproduced, thereby geometrical parameters and errors of the cone beam CT can be directly solved, the geometrical parameter calibration method is a systematized measurement solving method, the cone beam CT can beabstracted to be a basic camera system model, and then a plurality of correlative geometrical parameters in the system can be simultaneously solved. Compared with prior calibration methods, the geometrical parameter calibration method has the advantages that the geometrical parameters are not required to be measured one by one, repeated adjustment for the parameters one by one is not required, thereby the complexity level of calibration measurement of the whole system is greatly simplified, and simultaneously the stability of the cone beam CT geometrical calibration is improved.

Description

technical field [0001] The invention relates to a calibration method for an X-ray cone-beam computer tomography system (Computerized Tomography, referred to as cone-beam CT), in particular to a fixed relative position between an X-ray source and a flat-panel detector, and the X-ray source and a flat-panel detector The formed imaging subsystem rotates around a fixed rotation axis, or the sample to be measured is placed on a central turntable and rotates around a fixed rotation axis, while the imaging subsystem is fixed, so that the X-ray projection data of various angles can be obtained through the imaging subsystem. Calibration method of geometric parameters of small or miniature cone-beam CT system. Background technique [0002] Computed tomography system is an imaging method that uses known geometric conditions to reconstruct the density or attenuation rate in the tomography through multi-angle projection data, and has been widely used in medical clinical and industrial te...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B6/03G01N23/04G03B42/02
Inventor 王广志王梦蛟丁辉
Owner TSINGHUA UNIV
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