Radiography Apparatus Positional Offset Correction
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Solution Overview
Problem
In radiography apparatuses, particularly X-ray CT systems, the shuttle scan scheme causes positional discrepancies when moving a cradle in forward and backward directions, leading to inadequate image quality and fluctuating organ displays due to shifts in subject position, complicating diagnosis.
Innovation Solution
A radiography apparatus with a scanning table section that moves the cradle in both directions, acquiring and processing projection data to reconstruct forward-path and backward-path images, using an amount-of-positional-offset acquiring section to align pixel positions in both images, ensuring accurate registration and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cradle is moved in forward and backward directions during shuttle scan, then scan coverage and imaging efficiency are improved, but subject position shifts occur causing misalignment between forward-path and backward-path images
Solution Approach 1:
The patent replaces mechanical position alignment methods with image processing-based alignment. The amount-of-positional-offset acquiring section uses image comparison algorithms to detect and correct position shifts between forward-path and backward-path images, substituting mechanical precision requirements with computational image registration techniques.
Solution Approach 2:
The patent implements a feedback mechanism where the amount-of-positional-offset acquiring section continuously monitors position shifts between forward and backward scan images, and the image-reconstructing section applies real-time corrections based on detected offsets, creating a closed-loop system that maintains alignment accuracy throughout the scanning process.
2Productivity
If the cradle movement speed is increased to improve scanning efficiency, then productivity increases, but subject position stability deteriorates causing image fluctuations
Solution Approach 1:
The patent replaces mechanical position stabilization mechanisms with post-acquisition image processing. Instead of mechanically constraining the subject during high-speed cradle movement, the system captures images at high speed and then uses the amount-of-positional-offset acquiring section to computationally correct position shifts, enabling high-speed scanning without compromising stability.
Solution Approach 2:
The patent performs preliminary image acquisition at high speed, then applies position offset correction in subsequent processing steps. The amount-of-positional-offset acquiring section pre-calculates alignment corrections that are then applied during image reconstruction, allowing the system to maintain both high scan speed and position stability through sequential processing.
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 solution enhances image quality by ensuring that forward-path and backward-path images are correctly aligned, improving diagnostic efficiency by stabilizing organ positions and reducing image fluctuations.
Implementation Method 1
The X-ray tube emits toward the region to be imaged in the subject, for example, cone-shaped X-rays that radially extend in a channel direction
Data Source
AI summary
For the purpose of improving efficiency in diagnosis by performing image reconstruction for slice planes lying at the same position in a subject both in a forward direction FD and backward direction BD, an amount of positional offset ‘dz’ is acquired, which amount represents a difference in a body axis direction ‘z’ along the forward direction FD and backward direction BD between a first subject position and a second subject position, the first subject position being a position to which a region to be imaged in the subject laid on a cradle 401 is moved when the cradle 401 is moved in the forward direction FD, and the second subject position being a position to which the region to be imaged in the subject laid on the moving cradle 401 is moved when the cradle 401 is moved in the backward direction BD such that the region to be imaged in the subject coincides with the first subject position. Then, respective pixel positions in the forward-path image and backward-path image are corrected based on the amount of positional offset ‘dz’ such that the pixel positions lie at positions corresponding to each other in the body axis direction ‘z’ along the forward direction FD and backward direction BD.