Iterative Tomographic Image Reconstruction Attenuation Correction
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Solution Overview
Problem
Current tomographic image reconstruction methods, such as those used in Positron Emission Tomography (PET) and Computer Assisted Tomography (CAT), fail to adequately account for attenuation and scattering effects, leading to significant artefacts and reduced image quality due to the loss of photons and incorrect reconstruction of PET isotope density distributions in materials like kimberlite.
Innovation Solution
A method and system that iteratively update the tomographic image reconstruction by generating and refining an attenuation map, using a system matrix to account for voxel-specific attenuation and scattering probabilities, and repeating the reconstruction process until convergence, thereby compensating for these effects and reducing artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tomographic image reconstruction methods are used, then the reconstruction process is simple and fast, but significant artefacts are introduced and image quality is degraded due to unaccounted attenuation and scattering effects
Solution Approach 1:
The reconstruction process is segmented into multiple iterative steps: initial reconstruction, attenuation map generation, system matrix update, and image reconstruction. Each step handles a specific aspect of the attenuation and scattering correction, allowing the complex problem to be solved through manageable stages that progressively improve image quality while controlling computational complexity
Solution Approach 2:
An attenuation map is generated as a preliminary step before the final image reconstruction. This preliminary attenuation map captures the attenuation and scattering characteristics of the object, which are then used to update the system matrix in subsequent iterations, preparing the reconstruction process in advance to handle the complexity of photon interaction effects
2Measurement precision
If attenuation and scattering effects are not compensated for, then the reconstruction process is computationally efficient, but photon loss leads to incorrect representation of PET isotope density distributions
Solution Approach 1:
The reconstruction process uses feedback from the detected photon data to iteratively update the system matrix and refine the attenuation map. By continuously comparing the reconstructed image with the actual detector measurements and adjusting the system matrix accordingly, the method compensates for photon loss and accurately represents PET isotope density distributions despite attenuation and scattering effects
Solution Approach 2:
The system matrix is dynamically updated by changing parameters related to attenuation and scattering probabilities for each voxel based on the attenuation map. This parameter change allows the reconstruction algorithm to account for varying photon interaction characteristics throughout the object, correcting for photon loss and improving density distribution accuracy without requiring complete photon data
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
This approach significantly improves the fidelity of PET and CAT image reconstructions by accurately representing PET isotope density distributions, reducing artefacts, and enhancing the accuracy of material distribution maps in mineral detection applications.
Implementation Method 1
detector arrangement which comprises a plurality of detector elements, wherein the detector elements are configured to detect photons
Implementation Method 2
scattering refers to a physical process that changes the direction of a particle
Implementation Method 3
attenuations to a physical process that reduces the intensity of radiation, for example absorption of some of the particles
Implementation Method 4
scattering refers to a physical process that changes the direction of a particle
Data Source
AI summary
The invention relates to methods and systems for reducing artefacts in image reconstruction employed in tomographic imaging including Positron Emission Tomography (PET) and Computer Assisted Tomography (CAT) or (CT). The method is carried out entirely or in part by a computer or computerised system communicatively coupled to a detector arrangement which comprises a plurality of detector elements, wherein the detector elements are configured to detect photons associated with an object during PET and CAT screening processes in at least medical and mining applications.