Radiographic Afterimage Correction for Bone Density Accuracy
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Solution Overview
Problem
Radiographic imaging systems using flat panel detectors face challenges in correcting afterimages from initial imaging sessions, which can lead to high body thickness dependence in bone density measurements, making it difficult to obtain accurate bone density readings independent of subject thickness.
Innovation Solution
An image processing apparatus that estimates and corrects afterimages in subsequent radiographic images by using information from both low-energy and high-energy radiographic images, specifically by identifying soft tissue regions and performing afterimage amount estimation and correction to reduce body thickness dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radiographic images are captured sequentially using a flat panel detector, then the detector can be reused for subsequent imaging, but afterimages from previous imaging superimpose on subsequent images degrading measurement accuracy
Solution Approach 1:
The system performs preliminary afterimage correction by estimating the afterimage component from the current radiographic image and subtracting it before performing energy subtraction processing. This preliminary action removes the harmful afterimage effect that would otherwise degrade the accuracy of bone density measurements, enabling accurate measurements while maintaining detector reuse.
2Adaptability or versatility
If energy subtraction processing is performed on sequentially captured radiographic images, then bone images can be generated, but body thickness dependence increases due to afterimage superposition
Solution Approach 1:
Before performing energy subtraction processing to generate bone images, the system preliminarily estimates and removes the afterimage component from the radiographic images. This preliminary correction ensures that the subsequent energy subtraction processing operates on clean images without afterimage contamination, thereby generating bone images that are independent of body thickness variations.
Solution Approach 2:
The system introduces an intermediate afterimage estimation step that acts as a mediator between the raw radiographic images and the energy subtraction processing. By estimating the afterimage component as an intermediate representation and subtracting it, the system eliminates the body thickness dependence that would otherwise be introduced by direct energy subtraction on images containing afterimages.
3Ease of operation
If standard radiographic imaging is performed without afterimage correction, then imaging workflow remains simple, but bone density measurements exhibit high body thickness dependence
Solution Approach 1:
The system performs self-service by automatically estimating and correcting afterimages from the radiographic images themselves without requiring external calibration data or complex manual intervention. The afterimage estimation is derived directly from the current image data, enabling the system to self-correct measurement accuracy while maintaining workflow simplicity.
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 effectively reduces the body thickness dependence of bone density measurements, ensuring accurate and independent bone density readings, thereby meeting the required variation coefficient standards.
Implementation Method 1
the FPD is configured to perform digital image processing on captured images... converts incident radiation into visible light using a phosphor
Implementation Method 2
converts the visible light into electric charges by a photodiode
Data Source
AI summary
An image processing apparatus includes an image obtaining unit configured to obtain a first radiographic image and a second radiographic image, the first radiographic image being obtained by irradiating a subject with radiation of a first energy, the second radiographic image being obtained after the first radiographic image by irradiating the subject with radiation of a second energy different from the first energy, an estimation unit configured to estimate information about an afterimage of the first radiographic image in the second radiographic image based on information about a soft tissue region of the subject in the first radiographic image and the second radiographic image, and a correction unit configured to correct the second radiographic image using the information about the afterimage.