Prior Image Constrained Reconstruction for X-Ray CT
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Solution Overview
Problem
Current medical imaging technologies, such as x-ray CT and MRI, face challenges in reconstructing high-quality images from undersampled data sets, leading to artifacts like aliasing and streaking, and often require high radiation doses and lengthy scan times.
Innovation Solution
An image reconstruction method that incorporates prior image information to constrain the reconstruction process, using sparsifying transforms and iterative minimization techniques to produce high-quality images from fewer data samples, thereby reducing radiation exposure and scan time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If filtered backprojection technique is used to reconstruct images from transmission profiles, then image reconstruction can be performed, but image artifacts such as aliasing and streaking occur when data is undersampled
Solution Approach 1:
The patent applies preliminary action by using a prior image (obtained from a previous scan or preliminary scan) to constrain the reconstruction process before the actual image reconstruction takes place. This prior image provides anatomical information that guides the reconstruction algorithm, allowing accurate reconstruction from undersampled data without the typical artifacts. The prior image is integrated into the objective function that guides the iterative reconstruction process.
Solution Approach 2:
The patent changes the reconstruction parameters by incorporating prior image information and using an objective function that combines data fidelity terms with regularization terms based on the prior image. This parameter change allows the system to reconstruct images from fewer views (undersampled data) while maintaining image quality and suppressing artifacts that would normally appear with conventional filtered backprojection.
2Manufacturing precision
If the number of views is increased to suppress image artifacts, then image quality improves, but radiation dose and scan time increase
Solution Approach 1:
The patent uses a prior image obtained from a preliminary scan or previous scan to constrain the reconstruction of the current image. This preliminary information allows the system to achieve accurate reconstruction with fewer views, thereby reducing the radiation dose required while maintaining image quality. The prior image provides anatomical constraints that reduce the information needed from the current scan.
Solution Approach 2:
The patent uses a copy of the prior image (from a previous scan) to constrain the current reconstruction. This copied anatomical information is integrated into the reconstruction algorithm, allowing the system to reconstruct the current image with fewer new data samples, thus reducing radiation exposure while maintaining diagnostic quality.
3Manufacturing precision
If the number of views is increased to suppress image artifacts, then image quality improves, but scan time increases
Solution Approach 1:
The patent performs preliminary action by acquiring a prior image before the current scan. This prior image contains anatomical information that constrains the reconstruction process, allowing the system to achieve accurate reconstruction from fewer views and thus reducing scan time while maintaining image quality.
Solution Approach 2:
The patent uses a copy of the prior image to constrain the current reconstruction process. This copied anatomical information reduces the amount of new data needed, allowing faster scanning with fewer views while maintaining diagnostic image quality through the iterative reconstruction algorithm that incorporates the prior image constraints.
4Measurement precision
If beam intensity is increased to improve signal-to-noise ratio, then image quality improves, but radiation dose increases
Solution Approach 1:
The patent uses preliminary action by incorporating prior image information into the reconstruction process. This allows the system to achieve accurate reconstruction with lower beam intensity, maintaining signal-to-noise ratio while reducing radiation dose, because the prior image provides anatomical constraints that reduce the information needed from the current scan.
Solution Approach 2:
The patent changes the reconstruction parameters by using an objective function that incorporates prior image constraints. This parameter change allows the system to maintain image quality and signal-to-noise ratio with lower radiation doses, as the prior image information compensates for the reduced data quality from lower intensity beams.
Data Source
AI summary
A method for reconstructing a high quality image from undersampled image data is provided. The image reconstruction method is applicable to a number of different imaging modalities. Specifically, the present invention provides an image reconstruction method that incorporates an appropriate prior image into the image reconstruction process. Thus, one aspect of the present invention is to provide an image reconstruction method that requires less number of data samples to reconstruct an accurate reconstruction of a desired image than previous methods, such as, compressed sensing. Another aspect of the invention is to provide an image reconstruction method that imparts the signal-to-noise ratio of a prior image to the desired image being reconstructed. Another aspect of the invention is to provide an image reconstruction method that, when practiced in the field of x-ray imaging, allows for exposing a subject to substantially less radiation dose than is required in conventional x-ray imaging techniques.