Iterative X-ray CT Image Reconstruction Using Sector-Based System Matrix
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Solution Overview
Problem
Existing image reconstruction methods in X-ray CT systems face challenges with long image reconstruction times and high memory requirements, which compromise image quality when attempting to simplify the system matrix.
Innovation Solution
The method involves constructing a system model with concentric rings segmented into sectors, creating a system matrix associated with one view using sectors on projection lines, transforming this matrix for other views, and using it for iterative reconstruction with projection data to produce images composed of rectangular pixels, thereby simplifying the system matrix and reducing computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a stored matrix having been calculated in advance is used, then image reconstruction time is reduced, but a large memory capacity is required
Solution Approach 1:
The system model is divided into concentric rings with each ring segmented into multiple sectors. The system matrix is constructed by selecting only the sectors that lie on the projection lines for each view, rather than using all sectors. This segmentation approach reduces the number of matrix elements that need to be stored and processed, thereby reducing memory capacity requirements while maintaining reconstruction speed benefits.
2Loss of time
If the system matrix is simplified in order to shorten the image reconstruction time, then image quality deteriorates
Solution Approach 1:
The system matrix is constructed with local quality by selectively including sectors based on their relevance to each projection view. For each view, only the sectors intersected by the projection lines are included in the system matrix, with matrix elements representing the length of projection lines within each sector. This localized approach maintains sufficient detail for accurate image reconstruction while reducing overall matrix complexity and computation time.
3Manufacturing precision
If a system matrix is calculated at every time of image reconstruction, then image quality is maintained, but image reconstruction time gets longer
Solution Approach 1:
The system model with concentric rings and sectors is pre-configured before image reconstruction. The system matrix for each view is constructed by selecting sectors on projection lines from this pre-defined model, rather than calculating a complete system matrix from scratch. This preliminary structuring of the system model enables faster matrix construction during reconstruction while maintaining the accuracy needed for high-quality images.
Data Source
AI summary
The present invention is intended to provide an image reconstruction method based on an iterative reconstruction technique and characterized by a short image reconstruction time, a small memory capacity, and high image quality. The image reconstruction method comprises the steps of: constructing a system model that has a plurality of concentric rings each segmented into a plurality of sectors; constructing a system matrix associated with one view, by using some of all the sectors constituting the system model, the some of all sectors being located on respective projection lines concerning the one view; creating a system matrix associated with another view, by transforming the system matrix associated with the one view; reconstructing an image through iterative reconstruction by using the system matrix and projection data; and transforming the image into an image composed of rectangular pixels.