Method for determining geometrical calibration parameters in C-arm computed tomography system

Abstract

The invention discloses a method for determining geometrical calibration parameters in a C-arm computed tomography system, and particularly discloses a method for directly determining 9 geometrical calibration parameters in the C-arm CT system through a helix die body, belonging to the field of medical imaging. The method comprises the steps of using the geometrical features of a helix to skilfully switch the helix into a series of parallelograms; then obtaining the points of intersection of the parallelograms used for determining the projection of the coordinate axes of a die body coordinate system, and finally integrating the projection to a corresponding calibrated algorithm. Based on the extensively applied helix die body, the calibrated die body dose not need to be additionally processed, the method is an analytical method and makes the best of the information of mark points on the helix die body, so that the method has higher robustness and accuracy.

Description

technical field [0001] The present invention relates to an off-line calibration method in a C-arm tomography (C-arm CT) system, more specifically, it relates to a method for directly determining geometric calibration parameters in a C-arm CT system based on a helical phantom , belonging to the field of medical imaging. Background technique [0002] A C-arm tomography (C-arm CT) system integrated with a flat panel detector reconstructs a tomographic image of an object by obtaining a series of two-dimensional X-ray projection data. The C-arm imaging system is mainly composed of an X-ray source, a flat panel detector, and a C-arm frame. Compared with traditional CT, C-arm CT has the advantages of convenient movement and low price, especially its open design, which can be widely used in preoperative planning, intraoperative detection and result evaluation in interventional therapy. [0003] However, in practical applications, due to factors such as mechanical manufacturing, sy...

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Problems solved by technology

However, this method does not specifically describe the imaging system, such as the position of the X-ray source, the tilt and rotation angle of the detector, the distance from the source to the detector, etc., and in the case of a large system deviation, based on this method, the Reconstructed image quality may be suboptimal

[0005] Other researchers can obtain the specific calibration parameters of the system, but at this time the helical phantom is no longer applicable, and a special calibration phantom needs to be designed, which increases the additional workload

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