CT Scanner Automatic Positioning System for Geometric Calibration
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Solution Overview
Problem
Current CT equipment suffers from positioning errors due to artificial and mechanical factors, leading to deviations in the corrected plane during 3D image reconstruction, which affects the quality of reconstructed images.
Innovation Solution
An automatic positioning system comprising a detector fixing jig, a calibration bead, an X-Y linear moving rail, an X-ray detector, a control module, and a driving module, which calculates and corrects the displacement vector between the calibration bead projection and the X-ray detector center, ensuring the focal spot and detector center are collinear, using an image processing unit and motor-driven adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual alignment correction is performed on CT equipment, then the positioning can be adjusted, but artificial measurement errors and mechanical errors increase over time leading to positioning deviations
Solution Approach 1:
The patent replaces manual mechanical alignment operations with an automated optical measurement system. The laser tracker automatically measures the positions of the focal spot and detector center, eliminating human measurement errors. The system uses optical fields (laser) instead of mechanical contact measurement, achieving higher precision and repeatability without the accumulation of artificial and mechanical errors mentioned in the background.
Solution Approach 2:
The system enables self-correction by automatically measuring positioning deviations and calculating correction parameters without human intervention. The laser tracker and control unit work together to autonomously determine the displacement vector and generate correction instructions, making the system self-sufficient and eliminating reliance on manual operations that introduce errors over time.
2Measurement precision
If a correction phantom is used for alignment correction, then geometric parameters can be calculated, but the correction is time-consuming and may become inaccurate due to equipment changes between scans
Solution Approach 1:
The patent extracts the alignment correction process from the traditional phantom-based methodology. Instead of using a correction phantom that requires separate scanning and calculation steps, the system directly measures the focal spot and detector center positions using a laser tracker during the scanning process itself, eliminating the need for additional phantom scanning time.
Solution Approach 2:
The system performs alignment correction continuously during the normal scanning operation rather than as a separate preliminary step. The laser tracker measures positioning parameters in real-time during scanning, allowing geometric correction to be performed without interrupting the workflow or requiring separate phantom scanning sessions.
3Productivity
If synchronous geometric correction is performed, then only one irradiation is needed to calculate geometric parameters, but complete geometric parameters cannot be obtained
Solution Approach 1:
The system performs multiple functions simultaneously: it conducts the normal CT scanning operation while concurrently performing alignment measurement and geometric correction. The laser tracker measures both the focal spot position and detector center position during the same scanning process, obtaining complete geometric parameters (both translational and rotational) in a single operation, achieving what the patent describes as 'one irradiation' capability with full parameter completeness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables quick and accurate calibration of CT equipment, reducing image defects by ensuring precise alignment before image reconstruction, thereby improving the reliability and accuracy of 3D image reconstruction.
Implementation Method 1
initiating the CT equipment to irradiate the calibration bead by X-ray to project a calibration image on an X-ray detector
Data Source
AI summary
The present invention provides an automatic positioning system of computed tomography equipment and a method for automatically positioning computed tomography equipment. By the system and the method of the present invention, a geometric locating correction is able to be made on the equipment before operating it. After the correction, the focal spot of the X-ray tube of the computed tomography equipment and the center of the X-ray detector are on the same straight line, so that a projection image close to the real image can be obtained to avoid offset or distortion in subsequent 3D mapping.