Calibration method of new-type gravity-incorporating dual-plate X-ray machine

Abstract

The present invention provides a calibration method of a new-type gravity-incorporating dual-plate X-ray machine. A camera model is used to simulate an X-ray system, an analytical solution of parameters is obtained by direct linear transformation, the solution is used as an initial solution for a subsequent least squares problem, and a Levenberg-Marquardt optimization algorithm is used to continuean iterative method to complete calibration of a dual-plate X-ray system. In order to facilitate a subsequent gait research based on double-plate X-rays, a lead gravity line is introduced to measuredirection of gravity. In order to verify calibration accuracy, unit blocks are used to build a verification box embedded with steel balls. By comparing three-dimensional coordinates of the steel ballsrestored from the calibration parameters with errors of the three-dimensional coordinates measured by a manufacturer, reconstruction accuracy of root mean squared error (RMSE = 0.1847 mm) is achieved.

Description

technical field [0001] The invention relates to a calibration technology for a double-plate X-ray machine, in particular to a calibration method for a novel double-plate X-ray machine incorporating gravity. Background technique [0002] Biplane X-ray is a non-invasive, high-precision imaging method in orthopedic research. It has important applications in computer-aided preoperative planning, computer intelligent diagnosis, anatomical 3D reconstruction, biomechanical motion tracking and other fields. For example, in orthopedic research, it is often necessary to analyze bone kinematics data, and then compare the motion patterns of normal bones and abnormal bones, so as to reveal the mechanism of orthopedic diseases or evaluate postoperative effects. Due to its non-invasive and high-precision characteristics, dual-plane X-ray has gradually become the mainstream motion tracking method. The dual-plane X-ray system consists of two sets of X-ray equipment placed crosswise at a ce...

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Problems solved by technology

[0009] 2. The calibration box and the calibration method are developed and designed based on the C-arm machine of the Incremental, but it is not suitable for flat-panel X-ray machines, because the flat-panel is much larger than the Incremental, and it is not realistic to design a calibration box that can stick to the flat-panel

[0010] 3. Since the position of the double C-arm machine is different each time, the coordinate expression of gravity relative to the X-ray system will change every time, and it takes a lot of time to detect the direction of gravity each time, further reducing the efficiency

[0011] At present, manufacturers have developed a dual-plane X-ray system based on a flat-panel X-ray machine, but the corresponding calibration method is still blank

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