2D Antiscatter Grid Scatter Correction for Portable CT
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Solution Overview
Problem
Current antiscatter grid technologies for flat panel X-ray detectors in portable CT scanners do not adequately improve image quality, particularly for soft tissue imaging, due to residual scatter intensity and technical challenges in grid design.
Innovation Solution
A novel system integrating a two-dimensional (2D) antiscatter grid with a flat panel X-ray detector, featuring a 2D array of apertures separated by radiation-absorbing septa, and a method to correct residual scatter intensity using signal intensity variations in the detector pixel array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a 2D antiscatter grid is integrated with a flat panel detector, then scatter intensity is reduced and image quality is improved, but residual scatter intensity still reaches the detector and deteriorates image quality
Solution Approach 1:
The patent introduces a correction algorithm as an intermediary computational process that processes the detector signal to remove residual scatter components. The algorithm uses the known grid transmission characteristics and measured signal variations to calculate and subtract scatter contributions, thereby improving image quality despite the physical grid's inability to completely eliminate scatter.
Solution Approach 2:
The system implements feedback by using the detected signal intensity variations to inform the scatter correction process. The correction algorithm continuously adjusts scatter estimates based on the actual measured signal, creating a closed-loop system that compensates for residual scatter and maintains image quality.
2Object-affected harmful factors
If the 2D grid height is increased to reduce scatter transmission, then scatter rejection is improved, but technical and practical challenges arise that deteriorate image quality
Solution Approach 1:
The patent changes the parameter of grid height from a continuously variable dimension to a fixed, optimized value that balances scatter rejection with mechanical feasibility. By establishing specific grid height ranges and corresponding correction algorithms, the system achieves effective scatter reduction without the diminishing returns and practical challenges of excessive grid heights.
Solution Approach 2:
The patent replaces the purely mechanical approach of using taller grids for scatter rejection with a computational system. The correction algorithm substitutes for the need for excessively high physical grids by using signal processing to achieve scatter reduction, thereby avoiding the mechanical and practical challenges associated with very tall grid structures.
3Use of energy by moving object
If a 2D antiscatter grid is used, then primary x-ray transmission is improved, but the grid generates high and low fluence regions that cause pulse pile-up in photon counting detectors
Solution Approach 1:
The patent converts the harmful fluence modulation pattern into a beneficial tool for solving pulse pile-up. The same grid structure that creates high and low fluence regions is used to generate a known modulation pattern that, when detected, allows the system to identify and correct pulse pile-up errors through algorithmic compensation.
Solution Approach 2:
The system uses feedback by monitoring the fluence modulation pattern created by the grid and using this information to adjust the pulse pile-up correction algorithm. The known grid pattern serves as a reference signal that enables real-time detection and correction of pulse pile-up effects, maintaining detector accuracy despite the presence of modulation.
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 solution significantly enhances image quality by reducing scatter intensity, improving primary x-ray transmission, and correcting residual scatter, thereby achieving better CT number accuracy and contrast sensitivity in soft tissue imaging.
Implementation Method 1
a 2D array of apertures separated by radiation-absorbing septa
Implementation Method 2
a scintillator coupled to a photodetector array
Data Source
AI summary
A portable computed tomography (CT) system is provided herein. In an example, the portable CT system includes an O-shaped gantry defining an opening, an x-ray source operably coupled to the O-shaped gantry, a flat panel detector (FPD) coupled to the O-shaped gantry, and an antiscatter grid (ASG) operably coupled to a side of the FPD facing the opening of the O-shaped gantry. The FPD includes an x-ray absorbing sensor layer and a detector pixel array. The ASG includes a plurality of vertical walls defining open-ended channels and formed of a radiation-absorbing material. The open-ended channels are arranged in a geometric pattern pointed toward the x-ray source to receive x-rays in an x-ray emission path from the x-ray source.