Tomography Image Reconstruction Filter for Aliasing Artifact Reduction
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Solution Overview
Problem
Radiation tomography apparatuses face challenges in accurately reducing aliasing artifacts, which are inconsistent and difficult to detect due to their dependence on spatial resolution and sampling conditions, leading to variable and hard-to-cancel streak artifacts.
Innovation Solution
An image producing apparatus that calculates differences between images reconstructed using reconstruction filters with varying high-frequency enhancements, allowing for direct extraction and reduction of aliasing artifacts without relying on image analysis, thereby improving accuracy and reducing computational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the spatial frequency characteristics of a reconstruction filter are adjusted to suppress aliasing artifacts, then aliasing artifacts are reduced, but spatial resolution is compromised
Solution Approach 1:
The patent segments the frequency spectrum into mid-/low-frequency region and high-frequency region, applying different reconstruction filters to each region. The first reconstruction filter is optimized for mid-/low-frequency enhancement while the second filter is optimized for high-frequency enhancement, allowing independent optimization of each frequency band without compromising the other.
Solution Approach 2:
The patent applies local quality by making different parts of the reconstruction filter have different spatial frequency characteristics. Specifically, the filter is designed to have different degrees of enhancement in the high-frequency region while maintaining substantially identical enhancement in the mid-/low-frequency region, allowing targeted suppression of aliasing artifacts in high-frequency bands while preserving spatial resolution in mid-/low-frequency bands.
2Measurement precision
If image analysis methods are used to detect and reduce aliasing artifacts, then reduction accuracy may be improved, but computational cost increases
Solution Approach 1:
The patent performs preliminary action by calculating the difference between two images reconstructed with different reconstruction filters before the actual image production. This difference image, which contains information about aliasing artifacts, is pre-computed and then used to correct the final image, avoiding the need for complex real-time image analysis.
Solution Approach 2:
The patent creates a copy of the reconstruction process by using two different reconstruction filters to generate two images. The difference between these two images is then used to correct the original image, effectively copying the aliasing artifact pattern to enable its removal without requiring complex detection algorithms.
Data Source
AI summary
An image producing apparatus comprising a reconstructing unit configured to use a first reconstruction filter to reconstruct an image based on projection data collected by a scan on a subject to be imaged using a radiation source and a detector; a difference-calculating unit configured to calculate a difference between two images based on said projection data, said two images being reconstructed using second and third reconstruction filters respectively having spatial frequency characteristics such that degrees of enhancement in a mid-/low-frequency region are substantially identical to each other and degrees of enhancement in a high-frequency region are different from each other; and an image production unit configured to produce an image having reduced aliasing artifacts using said image reconstructed using said first reconstruction filter, and said difference.