Flexible Wedge Filter for X-ray Dose Uniformity in PCCT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In X-ray computed tomography (CT) imaging, particularly in photon counting CT (PCCT), there is a challenge in managing the dynamic range of X-ray doses, leading to overflow risks and increased noise due to mixed high and low dose data, which affects image reconstruction quality.
Innovation Solution
An X-ray imaging apparatus with a flexible wedge filter system that adjusts the X-ray transmission path length between the X-ray tube and the examinee, allowing for uniform distribution of the X-ray dose incident on the detector, reducing the dynamic range and minimizing overflow risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper limit of dose rate is set low to prevent overflow in X-ray photon measurement, then overflow risk is reduced, but data of significantly low dose becomes dominant and measurement noise increases
Solution Approach 1:
The patent divides the detection process into two separate detectors: a first detector for measuring high-dose X-ray photons with linear response characteristics, and a second detector for measuring low-dose X-ray photons with non-linear response characteristics. This segmentation allows each detector to be optimized for its specific dose range, preventing overflow in high-dose regions while maintaining measurement precision in low-dose regions.
Solution Approach 2:
The patent applies different detection characteristics to different spatial regions by assigning specific detectors to specific dose ranges. The first detector with linear response characteristics handles high-dose regions, while the second detector with non-linear response characteristics handles low-dose regions. This local optimization of detection quality resolves the contradiction between preventing overflow and maintaining measurement precision.
2Measurement precision
If photon counting is used to improve CT value quantitativity, then imaging precision is improved, but dynamic range becomes limited and overflow risk increases
Solution Approach 1:
The patent segments the photon counting process into two parallel paths with different detectors. The first detector performs photon counting with linear response for high-dose regions, while the second detector performs photon counting with non-linear response for low-dose regions. This segmentation extends the overall dynamic range while maintaining the quantitative precision benefits of photon counting.
Solution Approach 2:
The patent creates a composite detection system combining two different detector types with different response characteristics. By integrating a linear-response detector and a non-linear-response detector in a unified system, the patent achieves both high measurement precision and extended dynamic range, effectively resolving the contradiction between imaging precision and adaptability.
3Quantity of substance
If mixed high dose and low dose data are used in image reconstruction, then data completeness is improved, but noise from low dose data degrades image quality
Solution Approach 1:
The patent segments the data acquisition process by directing high-dose measurements to a first detector and low-dose measurements to a second detector. This segmentation allows both types of data to be collected simultaneously without mutual interference, maintaining data completeness while preventing noise degradation from low-dose data affecting high-dose measurements.
Solution Approach 2:
The patent introduces different detector types as intermediaries between the X-ray source and the image reconstruction process. The first detector with linear response characteristics acts as an intermediary for high-dose data, while the second detector with non-linear response characteristics acts as an intermediary for low-dose data. This intermediary approach allows mixed data to be used in reconstruction without noise degradation.
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 flexible wedge filter system effectively reduces the dynamic range of X-ray doses, minimizing noise and improving the reliability and precision of PCCT imaging by ensuring a uniform dose distribution, thereby enhancing image reconstruction quality.
Implementation Method 1
a wedge filter arranged between the X-ray tube and the examinee to attenuate a dose according to an X-ray from the X-ray tube
Data Source
AI summary
According to one embodiment, a flexible wedge filter is arranged between an X-ray tube and an examinee to attenuate a dose according to an X-ray from the X-ray tube. The flexible wedge filter has a plurality of filter modules 39 having a configuration capable of individually changing an X-ray transmission path length in an X-ray shielding material. The PCCT gantry controller individually operates the plurality of filter modules such that a dose according to an X-ray incident to an X-ray detector from the X-ray tube via the examinee is distributed substantially uniformly in spatial.