Weighted Analytic Filtered Back Projection for Asymmetric Cone-Angle Artifacts
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Solution Overview
Problem
Existing 3D cone beam reconstruction algorithms face challenges with asymmetric cone angle artifacts due to the unique geometric structure of multi-source static CT systems, where the center of the ray source ring and detector ring are not in the same plane, leading to incorrect weight calculations and artifacts.
Innovation Solution
A weighted analytic filtered back projection reconstruction method that divides the reconstruction region into multiple weight regions based on the relative positions of the ray source and detector rings, assigns different initial weights to each region, performs smooth transitions, and applies a final weight for accurate reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a symmetric weight calculation formula is used for cone beam reconstruction, then the reconstruction is simple and fast, but asymmetric cone angle artifacts appear when the ray source ring and detector ring are staggered
Solution Approach 1:
The patent divides the reconstruction region into multiple weight regions (first weight region and second weight region) based on the asymmetric geometric structure of the ray source ring and detector ring. Each region is assigned different weight calculation formulas appropriate to its location, allowing accurate correction of asymmetric cone angle artifacts while maintaining computational efficiency through region-specific processing.
Solution Approach 2:
The patent applies different weight calculation strategies to different spatial regions. The first weight region uses one weight formula while the second weight region uses another, ensuring that each local area is processed with the most appropriate correction method for its specific geometric characteristics, thereby eliminating artifacts without sacrificing overall reconstruction speed.
2Adaptability or versatility
If the ray source ring and detector ring are arranged in the same plane, then the cone angles are symmetric and simple weight formulas work, but the geometric structure cannot accommodate multi-row CT configurations
Solution Approach 1:
The patent segments the reconstruction space into distinct weight regions based on the staggered arrangement of ray source and detector rings. This segmentation allows the system to handle asymmetric multi-row CT geometries by applying appropriate weight corrections to each region, maintaining both geometric flexibility and reconstruction accuracy.
Solution Approach 2:
The patent explicitly addresses asymmetric cone angle geometry by introducing different weight calculation formulas for different regions. The method embraces the asymmetric configuration rather than trying to force symmetry, using the asymmetry itself as the basis for region definition and corresponding weight assignment to achieve accurate reconstruction.
3Device complexity
If a single weight formula is applied to all regions, then the calculation is uniform and simple, but incorrect results are obtained for near end cone angles in asymmetric configurations
Solution Approach 1:
The patent divides the reconstruction region into multiple weight regions and assigns different weight calculation formulas to each region. This segmentation enables accurate calculation of weights for both near end and far end cone angles by using the appropriate formula for each region, avoiding the errors that would result from a single universal formula.
Solution Approach 2:
The patent applies locally optimized weight calculation methods to different regions. Each region receives a weight formula specifically suited to its geometric characteristics, ensuring high calculation accuracy locally while maintaining overall system simplicity through the structured regional approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively compensates for asymmetric cone angle artifacts, improving the reconstructable range and accuracy of CT images, reducing the required ray dose, and extending the applicability of symmetric weight formulas to asymmetric configurations.
Implementation Method 1
acquiring the projection data volume of voxel points in each weight region irradiated by X-rays
Data Source
AI summary
Disclosed in the present invention are a weighted analytic filtered back projection reconstruction method and system for asymmetric cone angle artifacts. The method comprises the following steps: dividing a reconstruction area into a plurality of weight regions on the basis of relative positions of a ray source ring and a detector ring; acquiring the projection data volume of voxel points in each weight area irradiated by X-rays; according to the projection data volume of the voxel points in each weight area irradiated by the X-rays, assigning a different initial weight to each weight area; performing smooth transition on the initial weight of each weight area by means of a transition weight to form a final weight assigned to each weight area; and according to different final weights of the weight regions, performing final weighted analytic reconstruction on projection data p (α, β, γ) to acquire a back projection image.