Radiographic Scatter Correction Without Anti-Scatter Grids
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Solution Overview
Problem
Existing x-ray imaging techniques using anti-scatter grids reduce direct radiation, necessitating higher x-ray doses to compensate, which is detrimental in medical imaging, and existing mathematical methods require assumptions about tissue thickness.
Innovation Solution
A method that simulates x-ray interactions with materials to separate direct and scatter radiation without an anti-scatter grid, using a transfer function to reassign scatter photons as pseudo-direct radiation, improving contrast-to-noise ratio and reducing x-ray dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an anti-scatter grid is used to reduce scatter radiation, then image contrast is improved, but direct radiation is absorbed and x-ray dose must be increased
Solution Approach 1:
The invention extracts and removes the anti-scatter grid from the x-ray imaging system. Instead of using physical lamellae to block scatter, the system uses computational methods to identify and remove scatter radiation from the detected image, thereby eliminating the absorption of direct radiation by grid lamellae while still achieving scatter reduction
Solution Approach 2:
The invention replaces the mechanical anti-scatter grid system with a computational image processing system. The physical mechanical structure of the grid is substituted by mathematical algorithms that analyze the detected x-ray image and selectively remove scatter components based on their spatial and intensity characteristics
2Measurement precision
If x-ray flux is increased to compensate for photons lost in the anti-scatter grid, then image quality is maintained, but patient radiation dose increases
Solution Approach 1:
By removing the anti-scatter grid from the system, the invention eliminates the source of direct radiation absorption. This allows the system to maintain image quality without increasing x-ray flux, thereby reducing patient radiation dose while still achieving effective scatter reduction through computational methods
3Object-affected harmful factors
If mathematical methods are used to determine scatter photons without an anti-scatter grid, then x-ray dose can be reduced, but assumptions about tissue thickness are required
Solution Approach 1:
The invention implements a feedback mechanism where the system detects the actual x-ray image, analyzes the scatter patterns present, and uses this information to refine scatter removal. The system iteratively improves scatter correction by comparing expected scatter patterns with actual detected patterns, reducing reliance on fixed assumptions about tissue thickness
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
Enhances image quality by reducing scatter without grids, allowing lower x-ray doses and improved signal-to-noise ratio, particularly in medical imaging.
Implementation Method 1
When an object is subjected to x-ray radiation some of the x-ray photons are absorbed and some pass through the object, unscattered, to impinge on an x-ray detector
Implementation Method 2
An anti-scatter grid comprises a series of spaced apart parallel lamellae formed of x-ray absorbing material. A large proportion of scattered x-rays engages one of the lamella and is absorbed
Data Source
Figure 1a~1b
Figure 2
Figure 3a
AI summary
An x-ray imaging method comprises the steps of: providing a set of at least one training material, the set comprising different materials and/or different thicknesses of the or each material; obtaining observed x-ray images of the at least one training material with a pixellated detector; building a database in a simulator of simulated scatter kernels for variable parameters within the simulator for each of the at least one training material; generating a transfer function between parameters of the simulator and parameters of the observed image which is independent of sample type and thickness; generating a whole image scatter estimate; predicting the direct radiation for each scatter kernel; applying the transfer function to the scatter estimate and the direct radiation or the inverse of the transfer function to the observed intensity values; performing the calculation Z-S-D < threshold to provide scatter free data and/or a scatter free image.