Energy Subtraction Processing Using Thickness-Adjusted Absorption Coefficients
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Solution Overview
Problem
Energy subtraction processing in radiographic images, particularly in mammography, faces challenges in accurately extracting specific structures due to inadequate calculation of absorption coefficients, leading to artifacts in subtraction images.
Innovation Solution
An energy subtraction processing apparatus and method that acquires subject information including thickness and composition data, calculates appropriate absorption coefficients based on the energy distribution and substance composition, and uses these coefficients to determine weighting coefficients for accurate subtraction between radiographic images with different energy distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If energy subtraction processing is performed using fixed weighting coefficients, then the processing is simple and fast, but the extraction accuracy of specific structures deteriorates due to beam hardening effects
Solution Approach 1:
The patent pre-calculates and stores absorption coefficients for various thickness values before actual imaging. During energy subtraction processing, the system only needs to look up the pre-computed coefficients based on measured thickness, avoiding complex real-time calculations while maintaining high accuracy in extracting specific structures
Solution Approach 2:
The patent changes the absorption coefficient parameter dynamically based on the thickness of the subject. Instead of using fixed weighting coefficients, the system selects different absorption coefficients corresponding to different thickness values, thereby compensating for beam hardening effects and improving extraction accuracy
2Reliability
If absorption coefficients are not calculated considering subject thickness, then the processing is simple, but artifacts appear in the subtraction image
Solution Approach 1:
The system pre-computes absorption coefficients for a range of thickness values and stores them in a lookup table. During actual processing, the system measures the thickness and directly retrieves the corresponding absorption coefficient, eliminating complex real-time calculations while ensuring high-quality artifact-free subtraction images
Solution Approach 2:
The system automatically measures the thickness of the subject and uses this information to select the appropriate absorption coefficient from pre-computed data. This self-adjusting mechanism ensures optimal processing parameters are applied without manual intervention, maintaining both high image quality and processing efficiency
3Measurement precision
If weighting coefficients are determined using simple ratio of absorption coefficient differences, then the calculation is simple, but the subtraction image contains artifacts due to beam hardening
Solution Approach 1:
The patent determines weighting coefficients by changing the absorption coefficient parameter based on subject thickness. The system calculates absorption coefficients at different energy levels for the specific thickness, then derives weighting coefficients from these thickness-adjusted values, improving extraction accuracy while keeping the calculation method systematic and manageable
Solution Approach 2:
The system pre-calculates the relationship between thickness and absorption coefficients, storing this information for rapid retrieval. During processing, the system only needs to measure thickness and apply the corresponding pre-computed coefficients, achieving high accuracy without complex real-time computations
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 the generation of high-quality subtraction images with accurate extraction of specific structures, reducing artifacts and improving diagnostic accuracy by accounting for the thickness and composition of the subject.
Implementation Method 1
the fact that the attenuation amount of transmitted radiation differs depending on the substance forming the subject
Implementation Method 2
a phenomenon called beam hardening occurs in which the energy distribution of the detected radiation changes depending on the thickness of the substance
Data Source
AI summary
In an energy subtraction processing apparatus, method, and a non-transitory computer readable recording medium storing program, a high-quality image is generated by acquiring an absorption coefficient suitable for a subject. A subject information acquisition unit acquires the thickness information of a breast and a mammary gland content rate, as subject information, based on a low voltage image acquired by energy subtraction imaging. An absorption coefficient acquisition unit acquires an absorption coefficient corresponding to the subject information with reference to the relationship between the thickness of the breast and the X-ray absorption coefficient, which is calculated in advance. Based on the absorption coefficient acquired by the absorption coefficient acquisition unit, a weighting coefficient calculation unit calculates a weighting coefficient at the time of performing energy subtraction processing. A subtraction unit performs subtraction processing using the weighting coefficient calculated by the weighting coefficient calculation unit.