CT Image Reconstruction Switching Algorithms for Out-of-FOV Artifacts
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Solution Overview
Problem
Computed tomography (CT) image reconstruction algorithms often produce poor image results due to sensitivity to out-of-field-of-view (FoV) material, leading to image artifacts and compromised fidelity, especially when objects are positioned asymmetrically or with external materials within the scanner's bore.
Innovation Solution
An apparatus and method for CT image reconstruction that switches between two reconstruction algorithms based on the amount of out-of-FoV material, using a determiner to assess the material in the annular region and selecting a less sensitive algorithm when the threshold is exceeded, which includes a computationally cheaper initial reconstruction for exploratory images and iterative techniques like ART for higher fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a first reconstruction algorithm is used, then computational speed is maintained, but image fidelity deteriorates when out-of-FoV material is present
Solution Approach 1:
The system dynamically switches between two reconstruction algorithms based on the detected amount of out-of-FoV material. When out-of-FoV material exceeds a threshold, the system transitions from the first algorithm (faster, lower fidelity) to the second algorithm (slower, higher fidelity), making the reconstruction process adaptive to the imaging conditions rather than static.
Solution Approach 2:
The system changes the reconstruction algorithm parameter based on the measured out-of-FoV material. The out-of-FoV-determiner measures material in the annular region and uses this information to select the appropriate reconstruction algorithm, effectively changing the processing parameter to match the imaging scenario.
2Manufacturing precision
If a second reconstruction algorithm is used, then image fidelity improves, but computational complexity increases
Solution Approach 1:
The system applies the computationally intensive second reconstruction algorithm only partially - specifically when out-of-FoV material is detected above a threshold. For cases without significant out-of-FoV material, the simpler first algorithm suffices, avoiding unnecessary computational complexity while maintaining high fidelity when needed.
Solution Approach 2:
The reconstruction algorithm parameter is changed based on the out-of-FoV material measurement. The system selects between two algorithms with different computational complexities, adjusting the parameter to match the imaging conditions and avoid unnecessary computational burden.
3Reliability
If out-of-FoV material is present, then image artifacts increase, but the system must maintain processing efficiency
Solution Approach 1:
The system performs a preliminary measurement of out-of-FoV material using the out-of-FoV-determiner before executing the full reconstruction. This preliminary action allows the system to anticipate potential image quality issues and select the appropriate algorithm in advance, preventing artifacts before they occur while maintaining efficiency by avoiding unnecessary complex processing.
Solution Approach 2:
The system uses feedback from the out-of-FoV-determiner about the amount of out-of-FoV material to adjust the reconstruction algorithm selection. This feedback loop ensures that image quality is maintained by selecting the appropriate algorithm based on actual imaging conditions while preserving processing efficiency through intelligent decision-making.
Data Source
AI summary
An image reconstruction apparatus and related method. The amount of out- field-of view material for a CT scanner (IMA) with a given field of view (FoV) in a bore (B) is established. Based on the measurement, a hybrid-image reconstructor (RECONX) is configured to switch between different reconstruction algorithms.