X-ray CT Phantom Alignment via Image Processing
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Solution Overview
Problem
Existing methods for aligning phantoms in X-ray CT apparatuses are cumbersome and require skilled operators, as they rely on visual estimation and manual adjustments, leading to prolonged setup times and potential inaccuracies, especially in confirming the phantom's central positioning and handling horizontal lean.
Innovation Solution
The system generates tomographic image data to calculate displacement and gradient information, providing operators with precise alignment instructions, allowing for automatic or assisted alignment of the phantom's axis with the scan center and correcting its gradient, regardless of operator skill level, using a phantom retaining tool for controlled movement and tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual estimation and manual adjustments are used for phantom alignment, then operator skill can achieve accurate positioning, but the process becomes prolonged and burdensome
Solution Approach 1:
The patent replaces manual visual estimation and mechanical adjustment with an automated image processing system. The system captures a scanogram, processes it to detect the phantom's cylinder axis position and gradient, calculates alignment corrections, and guides automatic bed movement to reposition the phantom. This substitution of manual mechanical operations with automated image-based control resolves the contradiction by achieving high positioning accuracy without requiring prolonged manual adjustment time.
Solution Approach 2:
The patent enables the alignment system to self-correct positioning errors through automated feedback. The image processing unit automatically detects misalignment from the scanogram, calculates the required correction, and the bed positioning system executes the correction without operator intervention. This self-service mechanism eliminates the time-consuming iterative process of manual visual adjustment while maintaining high positioning accuracy.
2Measurement precision
If serial visual adjustment operations are performed to center the phantom, then positioning accuracy can be improved, but operator burden increases and the process becomes cumbersome
Solution Approach 1:
The patent replaces the complex series of manual visual adjustments with a single automated image processing and calculation system. The system captures one scanogram, automatically detects the cylinder axis position and gradient, calculates the precise correction needed, and executes bed movement to center the phantom. This eliminates the cumbersome iterative visual adjustment process while achieving high centering accuracy, significantly improving ease of operation.
Solution Approach 2:
The patent introduces an intermediate image processing unit that acts as a mediator between the raw scanogram data and the final phantom positioning. This intermediary system automatically extracts position and gradient information, calculates alignment corrections, and translates them into bed movement commands. This intermediary layer simplifies the operation by removing the need for operators to perform multiple visual estimation and adjustment iterations.
3Measurement precision
If manual visual measurement is used to determine phantom displacement, then operator judgment can guide correction, but accuracy is limited and time-consuming
Solution Approach 1:
The patent replaces manual visual measurement with an automated image processing system that calculates displacement based on the detected cylinder axis position in the scanogram. The system objectively determines the distance and direction from the phantom center to the scan center, eliminating the limitations of human visual judgment. This automated measurement achieves higher accuracy while significantly improving alignment efficiency by eliminating time-consuming manual assessment.
Solution Approach 2:
The patent implements an automated feedback loop where the scanogram is processed to detect phantom position, the displacement is calculated, and correction commands are generated and executed. This feedback mechanism continuously monitors and corrects phantom positioning based on objective image data rather than subjective visual estimation, improving both measurement precision and alignment efficiency through systematic automated control.
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
This approach significantly simplifies and accelerates the phantom alignment process, ensuring high precision and reducing operator burden, as it automates the alignment and correction of the phantom's position and gradient, enabling quick and accurate setup regardless of operator expertise.
Implementation Method 1
X-ray CT apparatus generates X-rays using an X-ray generator, and the X-rays that transmitted through an object on a bed are detected by an X-ray detector
Data Source
AI summary
The present invention comprises a top plate 31 for placing a cylindrical phantom 100, an X-ray tube 22 that generates X-rays, an X-ray detector 23 that detects X-rays transmitted through the phantom 100 placed on a top plate 31, a supporting body drive part 25 that rotates the X-ray tube 22 and X-ray detector 23, a tomographic image data generating part 60 that generates tomographic image data on the phantom 100 based on a results of detecting X-rays by the X-ray detector 23, a calculation processing part 80 that calculates displacement of the cylinder axis J of the phantom 100 relative to the center of rotation (center of scan) by the supporting body drive part 25, based on the tomographic image data, and the angle of gradient of the cylinder axis J relative to the normal direction (direction of slice) of the rotation plane of said rotation, and a monitor 5 that displays the calculated results.