Image Processing Device for Radiographic Beam Hardening Correction
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Solution Overview
Problem
Existing energy subtraction processes in radiography struggle to accurately separate soft part and bone part images due to beam hardening effects, leading to incomplete removal of unnecessary structures, as they rely on constant attenuation coefficients that do not account for varying tissue thickness and composition.
Innovation Solution
An image processing device and method that derive attenuation coefficients for soft and bone parts separately for each energy distribution, minimizing differences and using these coefficients to calculate optimal weighting coefficients for accurate subtraction of radiographic images, while also removing scattered ray components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same attenuation coefficient is used as the weighting coefficient in all pixels, then the calculation process is simplified, but it is difficult to completely remove unnecessary structures in the difference image because the thickness of soft part and bone part varies depending on the location
Solution Approach 1:
The patent applies local quality by deriving separate attenuation coefficients for soft part and bone part at each pixel location. Instead of using a single uniform attenuation coefficient, the system calculates location-specific attenuation coefficients that reflect the actual tissue thickness and composition at each position, thereby improving separation accuracy while accounting for anatomical variations
Solution Approach 2:
The patent implements dynamics by iteratively updating attenuation coefficients based on initial images and refining them through multiple calculations. The attenuation coefficients are not fixed but are dynamically adjusted based on the derived images from previous iterations, allowing the system to converge toward optimal separation accuracy
2Ease of manufacture
If attenuation coefficients are derived based on presumed values, then the process is simpler, but the bone part remains in the soft part image and the soft part remains in the bone part image due to varying tissue thickness
Solution Approach 1:
The patent applies feedback by using the derived soft part and bone part images from one iteration to update and refine the attenuation coefficients for the next iteration. The system continuously feeds back the separation results to improve the accuracy of attenuation coefficient derivation, progressively reducing the presence of unwanted structures in the separated images
Solution Approach 2:
The patent implements preliminary action by first deriving initial attenuation coefficients based on presumed values to create preliminary soft part and bone part images. These preliminary results serve as the foundation for subsequent refinement steps, where the attenuation coefficients are updated based on the actual tissue distribution revealed in the preliminary images
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 enables high-accuracy removal of unnecessary structures in difference images, improving the separation of soft and bone part images by considering the specific attenuation characteristics and thickness variations of tissues, thereby enhancing image quality.
Implementation Method 1
two radiation detectors that include a plurality of pixels accumulating charge corresponding to the emitted radiation
Implementation Method 2
a so-called beam hardening phenomenon occurs in which the energy distribution of the detected radiation changes depending on the thickness of the substance
Data Source
AI summary
An image acquisition unit acquires two radiographic images based on radiation which has different energy distributions and has been transmitted through a subject including a soft part and a bone part. An attenuation coefficient derivation unit derives a difference between a value of an attenuation coefficient of the soft part×a thickness of the soft part+an attenuation coefficient of the bone part×a thickness of the bone part and each pixel value of the radiographic image for each of the different energy distributions while changing the attenuation coefficient of the soft part for each of the different energy distributions, the thickness of the soft part, the attenuation coefficient of the bone part for each of the different energy distributions, and the thickness of the bone part from initial values and derives the attenuation coefficient of the soft part and the attenuation coefficient of the bone part for each of the different energy distributions at which the difference is minimized or the difference is less than a predetermined threshold value.