Tomosynthesis Image Reconstruction Using Non-Linear Signal Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Tomosynthesis imaging systems face challenges in preventing artifacts in reconstructed tomographic images, particularly in high-contrast areas and due to structures other than the structure of interest, while also dealing with increased computation time and noise enhancement.
Innovation Solution
A radiographic imaging system employing a frequency filtering processor, non-linear conversion processor, and back projection processor to produce band limiting image signals, perform non-linear conversion, and reconstruct tomographic images, respectively, which weights pixel values based on similarity between projection images to enhance the structure of interest and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear filter correction is applied during tomographic image reconstruction, then high frequency components are enhanced, but artifacts occur in high-contrast areas and noise components are excessively enhanced
Solution Approach 1:
The patent applies non-linear conversion to the filtered projection images before back-projection, transforming the linear filter correction approach into a non-linear process. This non-linear conversion dynamically adjusts the enhancement of different frequency components based on local image characteristics, preventing excessive enhancement in high-contrast areas while maintaining noise suppression benefits
Solution Approach 2:
The patent introduces a non-linear conversion process as an intermediary step between frequency filtering and back-projection reconstruction. This intermediary transformation modifies the filtered images to eliminate harmful artifacts before they are reconstructed into the final tomographic image, acting as a mediator that preserves beneficial frequency enhancement while removing detrimental effects
2Object-generated harmful factors
If successive approximation method is used for reconstruction, then artifact occurrence is reduced, but computation time increases
Solution Approach 1:
The patent performs non-linear conversion on the projection images before back-projection reconstruction, preparing the data in advance to prevent artifact formation during reconstruction. This preliminary non-linear transformation ensures that when back-projection is performed, the artifacts are already suppressed, avoiding the need for iterative successive approximation methods
Solution Approach 2:
The patent extracts and addresses the artifact problem at the preprocessing stage by applying non-linear conversion to the filtered projection images. By removing the harmful components before reconstruction, the method eliminates the need for post-reconstruction artifact correction that would require computationally intensive iterative methods
Data Source
AI summary
A radiographic imaging system is adapted to reconstruct a tomographic image in a given cross section of a subject from projection images of a subject acquired in tomosynthesis imaging. The radiographic imaging system comprises a frequency filtering processor for producing band limiting image signals having different frequency response characteristics from projection image signals corresponding to the projection images; a non-linear conversion processor for performing non-linear conversion of band limiting image signals to reduce a portion of band limiting image signals exceeding a given value; an integration processor for adding up band limiting image signals having undergone non-linear conversion through the non-linear conversion processor to produce converted image signals; and a back projection processor for reconstructing the tomographic image in the given cross section of the subject from the converted image signals corresponding to the projection images.