Photon-Counting CT Detector Switching for Flux-Dependent Imaging
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Solution Overview
Problem
Existing photon-counting X-ray CT detectors face challenges in adapting to varying x-ray flux and energy levels in both spatial and temporal domains, leading to issues such as charge sharing, cross-talk, and pile-up, which affect detector performance and image quality.
Innovation Solution
The X-ray CT apparatus features adjustable operating parameters in its photon counting circuits, allowing real-time adaptation based on x-ray count rates and energy distribution, optimizing pixel configuration, preamplifier settings, and signal shaping to enhance detector performance across different flux and energy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If smaller pixel pitch size is used to increase spatial resolution, then spatial resolution is improved, but charge sharing and cross-talk increase degrading detector performance
Solution Approach 1:
The patent applies dynamics by making the pixel configuration changeable in real-time based on x-ray flux conditions. The system switches between small pixel pitch mode for high spatial resolution and large pixel pitch mode for reduced charge sharing, allowing the detector to adapt dynamically to varying flux levels during CT scanning.
Solution Approach 2:
The patent changes the physical parameter of pixel pitch size based on operating conditions. By adjusting the pixel pitch from small to large configuration depending on x-ray flux levels, the system optimizes the balance between spatial resolution and charge sharing effects.
2Measurement precision
If longer signal integration time is used in preamplifier to improve energy resolution, then energy resolution is improved, but pile-up increases degrading detector performance under high flux
Solution Approach 1:
The patent makes the preamplifier integration time dynamic by adjusting it based on x-ray flux levels. During high flux conditions, the integration time is reduced to minimize pile-up, while during low flux conditions, longer integration time is used to maximize energy resolution.
Solution Approach 2:
The patent changes the electrical parameter of preamplifier integration time according to operating conditions. This parameter adjustment allows the system to optimize energy resolution when flux is low and reduce pile-up effects when flux is high.
3Reliability
If fixed pixel configuration optimized for high flux is used, then high flux handling capability is improved, but spatial non-uniformity in low flux regions cannot be addressed
Solution Approach 1:
The patent makes the detector system multi-functional by enabling it to operate in different pixel configurations for different flux conditions. The same detector can switch between small pixel mode for high flux regions and large pixel mode for low flux regions, providing universal adaptability across varying spatial and temporal flux distributions.
Solution Approach 2:
The patent introduces dynamic reconfigurability to the pixel configuration, allowing real-time adaptation to spatial non-uniformity in flux distribution. This enables the detector to optimize performance for both high and low flux regions within the same scanning procedure.
4Adaptability or versatility
If pixel configuration is adjusted based on previous view data, then adaptability is improved, but response speed is insufficient for dramatic flux changes between sequential views
Solution Approach 1:
The patent applies preliminary action by using data from previous views to pre-configure pixel settings before actual high-flux exposure. This anticipatory configuration allows the detector to be ready for expected flux patterns, improving response speed while maintaining adaptability.
Solution Approach 2:
The patent implements feedback by continuously monitoring flux patterns from previous views and using this information to adjust pixel configuration for subsequent views. This closed-loop approach enables the system to adapt to flux variations while maintaining fast response through learned patterns.
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 improves spatial uniformity and accuracy of x-ray detection by dynamically adjusting detector settings, reducing degradation from flux variations and enhancing image quality and data acquisition efficiency.
Implementation Method 1
Direct-conversion type semiconductor detectors of cadmium telluride (CdTe), cadmium zinc telluride (CZT), or the like
Data Source
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AI summary
An X-ray CT apparatus (1) according to an embodiment includes an x-ray source (12a), scan control circuity (33), a detector (13), photon counting circuits (42-n), connection circuitry (44) and processing circuitry (43). The scan control circuity (33) controls the x-ray source (12a) to expose a subject with x-rays over a scan having a plurality of views. The detector (13) is disposed to receive x-rays from the x-ray source (12a) and has plurality of pixels arranged in groups. The photon counting circuits (42-n) is provided for each of the pixels respectively. The connection circuitry (44) selectively connects, in a first mode, each pixel to one of the photon counting circuits (42-n) respectively and, in a second mode, each pixel in a group to a same one of the photon counting circuits (42-n). The processing circuitry (43), is connected to the connection circuitry (44) and the photon counting circuits (42-n), selects, for each of the views, the first mode or the second mode based upon a count rate of the x-rays.