Photon-Counting X-Ray Detector Pulse Timing for High-Flux Events
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Solution Overview
Problem
Photon-counting X-ray detectors suffer from coincident counting events that lead to adverse contamination of the X-ray spectrum, increased noise, poor spectral resolution, and reduced signal-to-noise ratio due to charge sharing and fluorescence processes, particularly in high-flux conditions.
Innovation Solution
A photon-counting X-ray detector with pixel elements equipped with comparators and monoflop units in a first signal processing stage, followed by delay units and counting elements in a second stage, to manage coincident counting events by normalizing pulse widths and correcting propagation times, thereby improving signal processing and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog charge summing is used to handle coincident counting events, then spectral resolution is improved, but pulse width and dead time increase significantly by a factor of 10-100
Solution Approach 1:
The patent divides the pixel array into multiple groups, with each group having its own dedicated summing circuit. This segmentation allows parallel processing of coincident events across different groups, reducing the overall dead time while maintaining spectral resolution through local charge summing within each group.
Solution Approach 2:
The patent implements preliminary charge summing within pixel groups before the main signal processing stage. By pre-summing charges from neighboring pixels that detect coincident photons, the system resolves coincident events early in the signal chain, preventing pulse width extension in subsequent amplification and discrimination stages.
2Object-affected harmful factors
If anti-coincidence logic is used to block simultaneous counting events in neighboring pixels, then noise from coincidence counts is reduced, but the number of recorded counting events decreases
Solution Approach 1:
The patent converts the harmful effect of coincident counting events into a beneficial signal by summing the charges from neighboring pixels that detect photons from the same interaction. Instead of blocking these events, the system uses the combined charge information to improve spectral resolution and accurately identify high-energy photons, thereby maintaining high counting rates while reducing noise.
3Measurement precision
If charge clouds are separated by electric field in converter material, then spatial resolution is improved, but coincident counting events in neighboring pixels increase
Solution Approach 1:
The patent merges the signals from neighboring pixels by summing their charges when coincident events are detected. This combining approach recovers the lost spatial information by attributing the summed charge to the appropriate pixel based on the event's true origin, thereby maintaining spatial resolution while accounting for charge sharing effects that cause coincident counts.
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 proposed solution enhances X-ray image data generation by reducing excessive degradation from signal pile-up, improving spectral resolution, and enabling precise signal processing even in high-flux situations.
Implementation Method 1
Incoming X-rays or photons can be converted into electrical signals in such X-ray detectors using a suitable converter material. X-ray photons, especially X-ray quanta, can be absorbed in the direct-conversion converter material. This can generate one or more charge clouds.
Implementation Method 2
The charge clouds are separated by an electric field in the converter material and, on their way to the pixel electrodes of pixel elements of the X-ray detector, induce an electrical signal in the pixel electrodes.
Implementation Method 3
The charge clouds are separated by an electric field in the converter material and, on their way to the pixel electrodes of pixel elements of the X-ray detector, induce an electrical signal in the pixel electrodes.
Data Source
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AI summary
The invention relates to a photon-counting X-ray detector, comprising a plurality of pixel elements and a converter element for converting X-rays into electrical signals, wherein in a first signal processing stage the pixel elements each have a comparator and a monoflop unit with a delay unit, wherein the comparator is designed to compare the electrical signal with a signal threshold and to provide a digital pixel signal to the monoflop unit, wherein the monoflop unit is designed to provide a pulse signal with a defined pulse length based on the digital pixel signal, wherein in a second signal processing stage outputs of the first signal processing stage are each signal-technically coupled to a delay unit, which is designed to provide the pulse signals with a respectively adapted delay to a respective counting element, wherein the respective counting element is designed toto count a counting signal as a function of the respective adjusted pulse signal. The invention further relates to a method for operating a photon-counting X-ray detector and an X-ray device.