CT Image Reconstruction with Offset Detectors
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Solution Overview
Problem
CT imaging devices with offset detector geometries often introduce artifacts such as cone-beam and shading artifacts during the reconstruction of truncated projection data, especially with asymmetric or non-iso-centered objects.
Innovation Solution
A method involving matching and splicing projection data from opposing sides of the acquisition trajectory to generate non-truncated data, differentiating, filtering with a Hilbert filter, applying redundancy weighting, and back-projecting to alleviate artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If offset detector geometry is used to increase field of view or reduce detector size, then device versatility and cost are improved, but projection data truncation occurs leading to reconstruction artifacts
Solution Approach 1:
The method performs preliminary actions by matching and splicing projection data from opposing sides of the acquisition trajectory before reconstruction. This preliminary data preparation extends the truncated projection data to cover the full object width, preventing artifacts during the subsequent reconstruction process while maintaining the benefits of offset detector geometry
Solution Approach 2:
The method introduces an intermediary processing step that acts as a mediator between the truncated projection data and the reconstruction algorithm. By matching and splicing data from opposing trajectories, the method creates complete projection data that bridges the gap caused by detector offset, enabling artifact-free reconstruction
2Productivity
If redundancy weighting is applied before filtering in conventional methods, then computational efficiency is improved, but artifact reduction effectiveness deteriorates
Solution Approach 1:
The method reverses the conventional order by performing the matching and splicing operation as a preliminary action before filtering and redundancy weighting. This ensures that complete projection data is available before any processing steps, maximizing artifact reduction effectiveness while maintaining computational efficiency through the optimized workflow
Data Source
Figure 1A~1B
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AI summary
A method and apparatus are provided to reconstruct projection data obtained from CT imaging devices with offset detector geometries. According to one aspect of the present invention, a method is provided to reconstruct projection data obtained from CT imaging devices with offset detector geometries that includes the following steps: (i) matching projection data measured at opposing sides of the acquisition trajectory and splicing them together to generate a full, non-truncated projection data set; (ii) differentiation of the projection data; (iii) filtering the differentiated projection data with a filter, such as for example a Hilbert filter; (iv) applying redundancy weighting to the filtered projection data; and (v) back-projecting the redundancy weighted projection data to generate image data.