Redundancy-Weighted Image Reconstruction for Off-Center X-Ray Tomography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Off-center detector X-ray tomography systems face challenges in reconstructing high-quality images due to redundancy artifacts when using short scans, particularly when the detector is positioned asymmetrically, leading to truncated projections and sampling redundancies across multiple arcs.
Innovation Solution
A device and method for off-center detector X-ray tomography that employs a uniform redundancy weighting function based on the union of arcs traversed by the focus point during two rotational passes, ensuring accurate image reconstruction by compensating for redundant sampling across both passes, which avoids image artifacts and allows for efficient scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a short scan is used with an off-center detector, then scanning time is reduced, but redundancy artifacts appear in the reconstructed image
Solution Approach 1:
The patent applies Parker weighting, which is a parameter-based correction method that adjusts the weight of projection data based on the redundancy factor. By changing the weighting parameter from uniform to redundancy-weighted, the system maintains image quality while using short scans with off-center detectors.
Solution Approach 2:
The patent specifically addresses the asymmetric positioning of the detector relative to the X-ray source. The redundancy weighting function is designed to account for the asymmetric sampling pattern that occurs when the detector is offset from the center, allowing short scans to be performed without introducing artifacts.
2Area of stationary object
If the detector is positioned off-center, then field-of-view is extended, but projection data becomes truncated
Solution Approach 1:
The redundancy weighting function compensates for the truncated projection data by adjusting weights based on the actual sampling coverage. This allows the system to use off-center detector positioning to extend field-of-view while maintaining complete sampling of the object through mathematical correction.
3Reliability
If redundancy weighting is applied, then image artifacts are reduced, but computational complexity increases
Solution Approach 1:
The patent implements redundancy weighting by modifying the projection data weights before reconstruction. This parameter-based approach integrates smoothly into existing reconstruction algorithms, adding computational steps but avoiding the need for completely complex reconstruction methods.
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 enables high-quality image reconstruction by uniformly weighting projection data across both rotational passes, effectively reducing redundancy artifacts and ensuring complete sampling of the object's field-of-view, even with an off-center detector, thereby improving image fidelity and efficiency.
Implementation Method 1
Modern X-ray tomography devices use X-ray sources which emit a diverging beam, such as a fan beam or a cone beam. The beam traverses an examination region including an object to be imaged, and is intercepted by a detector, which comprises an array of detector elements for detecting incident X-ray radiation.
Data Source
AI summary
The invention relates to off-center detector X-ray tomography reconstruction of an image of an object on the basis of projection data acquired during a rotation of an X-ray source and the off-center detector around the object in two rotational passes of less than 360°, wherein a focus point of the X-ray beam travels along largely overlapping arcs (401, 402) in the two rotational passes, the off-center detector being positioned asymmetrically with respect to a central of the X-ray beam and a direction of a detector offset being reversed between the passes. According to the invention, redundancy weighting of the projection data with respect to a redundant acquisition of projection values during each of the rotational passes is made using a redundancy weighting function determined on the basis of a union of the arcs (401, 402).