Photon-Counting X-Ray Detector Layout for Clinical Phase Contrast
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Solution Overview
Problem
Existing x-ray imaging systems, particularly in clinical settings, struggle to achieve phase contrast imaging efficiently due to high radiation doses, scanning time requirements, and pile-up issues in photon detection, which are impractical for clinical applications.
Innovation Solution
An x-ray imaging system utilizing a photon-counting x-ray detector with edge-on oriented detector sub-modules, each comprising detector elements with two opposite sides of different potentials, enabling charge drift and allowing for the estimation of charge diffusion to determine the point of interaction, thereby improving resolution and enabling phase contrast imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional x-ray imaging systems use scanning methods and analyzer gratings to achieve phase contrast imaging, then imaging capability is improved, but radiation dose increases and scanning time increases
Solution Approach 1:
The patent removes the analyzer grating (G2) from the conventional grating interferometer setup, extracting the harmful component that absorbs radiation and requires higher doses. By using a G2-less configuration with a phase shift grating (G1) that does not absorb x-rays, the system achieves phase contrast imaging without the radiation penalty associated with traditional analyzer gratings.
Solution Approach 2:
The patent changes the fundamental detection parameter from continuous analog signal to photon-counting events. By using a photon-counting detector that records individual photon interactions and their positions, the system achieves superior contrast-to-noise ratio and spatial resolution without requiring the high radiation doses needed by conventional systems to overcome statistical noise.
2Productivity
If conventional detectors are used with high flux to avoid motion artifacts, then imaging speed is improved, but pile-up effects occur reducing measurement precision
Solution Approach 1:
The patent segments the detection process into discrete photon-counting events rather than continuous analog measurement. Each photon interaction is counted as a separate event with recorded position and energy, allowing the system to handle high flux rates without pile-up effects. The depth-segmented detector further divides the detection volume into multiple layers, assigning each photon to a specific depth segment.
Solution Approach 2:
The patent replaces the mechanical/scanning-based imaging approach with a direct photon-counting detection system. Instead of mechanically scanning gratings or using continuous analog detection that is prone to pile-up, the system uses electronic photon-counting electronics that can distinguish individual photon events even at high flux rates, substituting mechanical complexity with electronic precision.
3Device complexity
If charge diffusion is not accounted for in the detector, then device complexity is reduced, but manufacturing precision and resolution are compromised
Solution Approach 1:
The patent introduces feedback through software processing that uses the detected charge diffusion pattern to calculate and correct the actual point of interaction. By measuring the spread of charge carriers during drift and using this information to computationally determine the precise interaction location, the system achieves high resolution without additional physical components or complex detector structures.
Solution Approach 2:
The patent replaces physical methods of improving resolution (such as smaller pixel sizes or additional optical elements) with a computational approach. By using software algorithms to process charge diffusion patterns and determine interaction points, the system achieves high spatial resolution without the manufacturing complexity and physical constraints of traditional hardware-based resolution improvement methods.
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 system achieves significantly improved resolution and enables feasible clinical phase contrast imaging, such as for CT, by determining the point of interaction through charge diffusion, reducing the need for analyzer gratings and minimizing radiation dose.
Implementation Method 1
determine an estimate of charge diffusion originating from a Compton interaction or an interaction through photoeffect related to an incident x-ray photon
Implementation Method 2
determine an estimate of charge diffusion originating from a Compton interaction or an interaction through photoeffect related to an incident x-ray photon
Implementation Method 3
Each detector sub-module has a thickness with two opposite sides of different potentials to enable charge drift towards the side, where the detector elements are arranged
Data Source
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AI summary
There is provided an x-ray imaging system (100) comprising an x-ray source (10), and an associated x-ray detector (20), wherein the x-ray detector (20) is a photon counting x-ray detector for enabling detection of photon-counting events. The x-ray imaging system (100) is configured for enabling acquisition of at least one phase contrast image based on detected photon-counting events. The x-ray detector (20) is based on a number of x-ray detector sub-modules, also referred to as wafers, each of which comprises detector elements, wherein the x-ray detector sub-modules are oriented in edge-on geometry with their edge directed towards the x-ray source, assuming the x- rays enter through the edge. Each x-ray detector sub-module or wafer has a thickness with two opposite sides of different potentials to enable charge drift towards the side, where the detector elements, also referred to as pixels, are arranged. The x-ray imaging system (100) is further configured to determine an estimate or measure of charge diffusion originating from a Compton interaction or an interaction through photoeffect related to an incident x-ray photon in an x-ray detector sub-module or wafer of the x-ray detector, and to determine an estimate of a point of interaction of the incident x-ray photon in the x-ray detector sub-module based on the determined estimate or measure of charge diffusion.