Mass Density Imaging via Refraction and Regularized Inversion
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Solution Overview
Problem
Conventional x-ray radiography methods face challenges in producing high-quality images at higher x-ray energy levels due to noise artifacts, which affect the accuracy of mass density imaging, especially in clinical applications where photon-limited conditions prevail.
Innovation Solution
A method involving a regularized mathematical inversion algorithm, specifically a constrained least-squares filter, is applied to refraction images obtained from Diffraction Enhanced Imaging (DEI) or Multiple-Image Radiography (MIR) to derive a mass density image, mitigating noise artifacts and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radiography uses lower x-ray energy to achieve better absorption contrast, then image contrast is improved, but x-ray dosage increases and image quality deteriorates due to noise
Solution Approach 1:
The patent changes the imaging parameter from absorption-based to refraction-based imaging. By measuring refraction angles instead of absorption, the system can use higher x-ray energies while maintaining image quality and reducing dosage. The refraction signal provides contrast through angular deviations caused by density variations, eliminating the need for low-energy high-dosage absorption imaging.
Solution Approach 2:
The patent replaces the conventional absorption-based detection mechanism with a refraction-based detection mechanism using diffraction-enhanced imaging. This substitution allows the system to exploit refraction effects rather than absorption, enabling higher energy imaging with reduced dosage while maintaining or improving contrast.
2Object-affected harmful factors
If conventional radiography uses higher x-ray energy to reduce dosage, then x-ray dosage decreases, but image quality lessens due to reduced absorption contrast
Solution Approach 1:
The patent changes the fundamental imaging parameter from absorption to refraction. By measuring refraction angles through diffraction-enhanced imaging, the system maintains image quality at higher energies where absorption contrast is poor. The refraction signal remains strong at higher energies, allowing dosage reduction without quality loss.
3Measurement precision
If refraction-angle images are used to depict detailed object features, then image detail is improved, but streak artifacts increase due to noise in photon-limited conditions
Solution Approach 1:
The patent introduces an intermediary computational step using a regularized inversion algorithm that acts as a mediator between the refraction-angle data and the final mass density image. This intermediary process filters out streak artifacts and noise while preserving the detailed structural information, producing a reliable mass density image from the refraction data.
Solution Approach 2:
The patent replaces direct refraction-angle imaging with computed mass density imaging through mathematical inversion. This substitution transforms the noisy refraction data into a cleaner mass density representation, eliminating streak artifacts while maintaining detail through the regularized inversion process.
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 eliminates streak artifacts and enhances the quantitative accuracy of mass density images, allowing for better contrast and detail similar to conventional radiography while using higher x-ray energy levels at lower doses, thus improving diagnostic imaging in medical applications.
Implementation Method 1
the quantity depicted at each pixel in a DEI or MIR refraction-angle image is the angle Δθ by which an x-ray beam is refracted upon passing through the object
Implementation Method 2
DEI and multiple-image radiography (MIR) are related phase-sensitive x-ray imaging methods, which generally use a system of diffracting crystals to analyze the angular components of an x-ray beam
Data Source
AI summary
A method for detecting a mass density image of an object. An x-ray beam is transmitted through the object and a transmitted beam is emitted from the object. The transmitted beam is directed at an angle of incidence upon a crystal analyzer. A diffracted beam is emitted from the crystal analyzer onto a detector and digitized. A first image of the object is detected from the diffracted beam emitted from the crystal analyzer when positioned at a first angular position. A second image of the object is detected from the diffracted beam emitted from the crystal analyzer when positioned at a second angular position. A refraction image is obtained and a regularized mathematical inversion algorithm is applied to the refraction image to obtain a mass density image.