3D CT Image Reconstruction via Collimation Overlap and Filtering
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Solution Overview
Problem
Computed Tomography (CT) image reconstruction using axial step-and-shoot technique often results in shading artifacts due to poor sampling, filtering, and collimation errors, which degrade the quality of reconstructed medical images.
Innovation Solution
A system and method that determine intermediate image locations and filtering kernels based on scanning parameters and requested reconstruction parameters to reduce artifacts, including the introduction of at least 10% collimation overlap between axial scans and reconstruction of thin images followed by broadening in image space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If axial step-and-shoot scanning is used for CT image acquisition, then scanning efficiency is improved, but shading artifacts and data inconsistencies occur due to poor sampling and collimation errors
Solution Approach 1:
The patent introduces a preliminary action by adding collimation overlap between consecutive axial scans before reconstruction. Specifically, the collimation of the (N+1)-th scan overlaps with the N-th scan by at least 10% of the detector width, ensuring that each image location is sampled by multiple adjacent scans. This preliminary overlapping action prevents data inconsistencies and shading artifacts that would otherwise occur in standard step-and-shoot acquisition.
Solution Approach 2:
The patent applies partial or excessive action by acquiring more scanning data than strictly necessary for basic image reconstruction. The collimation overlap ensures that each image location is sampled by more than one scan, creating redundant data that exceeds the minimum requirement. This excessive sampling approach eliminates shading artifacts and improves reconstruction quality while maintaining scanning efficiency.
2Speed
If standard axial step-and-shoot reconstruction is performed, then reconstruction speed is maintained, but shading artifacts and pinwheel artifacts appear due to poor filtering and sampling
Solution Approach 1:
The patent introduces an intermediary filtering step between data acquisition and final image reconstruction. A filtering kernel is applied to the scanning data to reduce shading artifacts, overshoots, and pinwheel artifacts before reconstruction. This intermediary filtering operation improves image quality without significantly compromising reconstruction speed, as the filtering is performed on the already-acquired data.
3Manufacturing precision
If collimation overlap of at least 10% is introduced between axial scans, then shading artifacts are reduced, but scanning time increases
Solution Approach 1:
The patent applies partial or excessive action by introducing a minimal but sufficient collimation overlap of at least 10% between consecutive scans. This overlap is excessive enough to eliminate shading artifacts and ensure proper sampling, but partial enough to minimize the increase in scanning time. The overlap ensures that each image location is sampled by multiple scans without requiring full redundancy.
Data Source
AI summary
The disclosure relates to system and method for CT image reconstruction. The method may include: obtaining scanning data, wherein the scanning data is generated by at least one detector via a plurality of axial scans; obtaining a scanning parameter wherein the scanning parameter include a detector size; obtaining a requested reconstruction parameter; determining a plurality of requested image locations based on the scanning parameter and the requested reconstruction parameter; determining an intermediate reconstruction parameter based on the requested reconstruction parameter; determining a plurality of intermediate image locations based on the plurality of requested image locations and the intermediate reconstruction parameter; determining a intermediate image volume based on the plurality of intermediate images and the scanning data; determining a final image volume based on the intermediate image volume and a filter; reconstructing an image of the subject based on the final image volume and the requested reconstruction parameters.