CT Projection Correction Using Hypothetical X-Ray Spectra
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Solution Overview
Problem
Existing X-ray CT technologies face challenges in reducing beam hardening and scattering artifacts in reconstructed images due to the need for a structure with a known linear absorption coefficient and the difficulty in incorporating varying absorption information depending on X-ray incidence modes.
Innovation Solution
An information processing system that acquires projection data and an absorption model, generates corrected projection data using hypothetical incident X-rays, calculates a consistency index, and outputs data based on this index to reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is performed using spectra of incident X-rays estimated by applying X-rays to a structure with a known linear absorption coefficient, then beam hardening artifacts can be reduced, but the method requires a structure with known linear absorption coefficient and cannot account for varying absorption information depending on X-ray incidence modes
Solution Approach 1:
The patent creates a virtual copy of the object to be measured using hypothetical absorption coefficient distributions. Instead of requiring a physical structure with known absorption coefficients, the system generates multiple hypothetical models that represent possible absorption patterns, then selects the most appropriate one based on consistency evaluation.
Solution Approach 2:
The patent changes the approach from using fixed known absorption coefficients to using multiple hypothetical absorption coefficient distributions with varying parameters. By generating multiple candidate models with different absorption characteristics and evaluating their consistency, the system adapts to the actual absorption behavior without requiring prior knowledge of the object's structure.
2Ease of operation
If a hypothetical model is used for spectrum estimation, then the process can be simplified, but the model has difficulty incorporating information such as absorption edge and scattering that vary depending on the mode of incidence
Solution Approach 1:
The patent introduces dynamic selection of absorption coefficient distributions based on consistency evaluation. Instead of using a single static hypothetical model, the system generates multiple hypothetical models and dynamically selects the most appropriate one by evaluating which model produces the most consistent corrected projection data across different views and energies.
Solution Approach 2:
The patent implements a feedback mechanism where the corrected projection data from each hypothetical model is evaluated for consistency. The consistency of corrected projection images from different views serves as feedback to determine which hypothetical absorption coefficient distribution best represents the actual object, thereby retaining important absorption information while maintaining model simplicity.
3Measurement precision
If multiple hypothetical incident X-rays are used for correction, then more accurate correction can be achieved, but the calculation complexity increases due to generating corrected projection data for each candidate
Solution Approach 1:
The patent applies partial action by generating corrected projection data for multiple hypothetical incident X-rays but only selecting the most consistent one for final image reconstruction. Instead of combining all corrections, the system performs partial correction using only the best-matching hypothetical model, reducing unnecessary computational overhead while maintaining correction accuracy.
Solution Approach 2:
The patent performs preliminary evaluation of consistency for each hypothetical model before final reconstruction. By calculating a consistency index in advance for each candidate model and selecting the best one beforehand, the system avoids the time-consuming process of performing full reconstruction with multiple models, thus reducing overall calculation time while maintaining accuracy.
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 system effectively reduces artifacts by flexibly incorporating X-ray absorption information, improving the quality of reconstructed images.
Implementation Method 1
an absorption model related to a mode of absorption of X-rays by the object to be measured
Data Source
AI summary
An information processing system is provided, including circuitry configured to: acquire projection data representing an X-ray CT projection image related to an object to be measured and an absorption model related to a mode of absorption of X-rays by the object, the projection data including information on the projection image(s) corresponding to azimuths where incident X-rays are applied to the object; generate corrected projection data for each candidate of hypothetical incident X-rays, the corrected projection data being the projection data in which correction on the basis of the candidate of hypothetical incident X-rays and the absorption model is performed; calculate a consistency index indicating a degree of consistency of the corrected projection images corresponding to the azimuths for each of the corrected projection data generated; and an output unit configured to output, on the basis of the consistency index, at least one piece of the corrected projection data generated.