X-Ray CT Marker Layout for Focal Point Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing X-ray CT devices face challenges in accurately detecting the position of the X-ray focal point during a CT scan due to variations caused by thermal expansion or target deterioration, leading to spatial distortion and reduced dimensional measurement accuracy, and existing methods either obstruct the imaging field, require complex marker positioning, or increase device costs.
Innovation Solution
An X-ray CT device with a marker member featuring a flat plate with markers at two positions, allowing simultaneous imaging of markers and subjects without superimposition, and using image processing to detect feature points, calculate focal point movement, and correct the coordinate system for distortion-free tomographic reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a marker is used to detect the X-ray focal point position, then the focal point position can be detected, but the marker obstructs the imaging visual field of the subject
Solution Approach 1:
The marker is positioned in the depth dimension (along the X-ray beam path) rather than in the imaging plane, allowing it to be detected by the X-ray detector without obstructing the subject's imaging visual field. This spatial arrangement in three dimensions resolves the contradiction between marker detection and subject imaging.
2Object-generated harmful factors
If the marker is positioned to allow simultaneous imaging with the subject, then the visual field is not obstructed, but the position detection accuracy is reduced due to superimposition
Solution Approach 1:
By placing the marker at a different depth position along the X-ray beam path compared to the subject, the marker's projection falls on a different region of the detector or can be distinguished through depth-based separation. This dimensional separation allows simultaneous imaging without superimposition, maintaining both visual field clarity and position detection accuracy.
3Measurement precision
If a highly accurate marker positioning mechanism is used to reproduce reference position, then the focal point position can be accurately detected, but the device complexity and fabrication load increase
Solution Approach 1:
The marker is designed to be automatically positioned and detected through the X-ray imaging system itself, without requiring separate positioning mechanisms or complex reproduction systems. The marker's position is detected directly by the X-ray detector, and the system self-calibrates by detecting the marker's position in the projection image, eliminating the need for complex mechanical positioning devices.
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
Enables high-dimensional measurement accuracy by three-dimensionally detecting the focal point position and correcting geometric errors, resulting in distortion-free tomographic images suitable for precise three-dimensional shape measurement.
Implementation Method 1
an X-ray source that generates an X-ray
Implementation Method 2
a flat plate 21 formed with markers M
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Between an X-ray source and a rotating stage 13, a marker member including a flat plate 21 formed with markers M and a support part 22 supporting the flat plate 21 is arranged. The formation positions of the markers M on the flat plate 21 are set to positions that allow the distance between the markers M to be most separated in an area in which both of the markers M are not superimposed on a projection image of a subject within the detection range of an X-ray detector 12 and that is constantly included within the detection range even when an X-ray focal point is moved. Also, the length of the support part 22 is adjusted to a length resulting in a side end of the detection range of the X-ray detector where the flat plate 21 and the markers M are not superimposed on the subject W on a projection image.