Photon-Counting Spectral Detector Pulse Separation
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Solution Overview
Problem
Photon-counting radiation detectors face issues with 'pile-up' where overlapping pulses result in lost counts and artifacts in x-ray images, affecting the quality of both spectral and conventional images.
Innovation Solution
A radiation detector with detection circuitry producing pulse-like signals and an energy estimating circuit that detects incident photons independently of threshold comparisons, using a registration circuit to identify local maxima in the output signal, allowing for separate detection of overlapping pulses and reducing lost counts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If threshold comparison method is used to detect photon energies, then energy bin determination is achieved, but pulse overlap causes lost counts and detection accuracy deteriorates
Solution Approach 1:
The detection method is segmented into two independent circuits: an energy estimating circuit that performs threshold comparisons for energy bin determination, and a registration circuit that independently detects photon arrival times by identifying local maxima. This segmentation allows each circuit to specialize in one function, preventing the threshold comparison from interfering with photon counting during pulse overlap.
Solution Approach 2:
The registration circuit acts as an intermediary that captures photon arrival information from the output signal independently of the threshold comparison process. By detecting local maxima without relying on threshold crossings, it mediates between the energy measurement process and the final photon count, ensuring accurate counting even when pulses overlap and threshold comparisons fail.
2Device complexity
If conventional threshold-based photon counting is used, then simple counting is achieved, but overlapping pulses result in lost counts
Solution Approach 1:
The detection system is divided into two parallel circuits with distinct functions: the energy estimating circuit maintains simplicity for energy determination, while the registration circuit adds specialized functionality for reliable photon counting by detecting local maxima. This segmentation allows the system to maintain overall simplicity while adding only the necessary complexity to solve the pulse overlap problem.
Solution Approach 2:
The registration circuit changes the detection parameter from threshold crossing (used in conventional counting) to local maximum detection. This parameter change enables the system to reliably detect photon arrivals even when pulses overlap, as local maxima remain distinguishable features in the output signal even during pile-up conditions.
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 significantly reduces lost counts and improves the accuracy of both spectral and conventional x-ray images by enabling the detection of overlapping pulses, enhancing image quality.
Implementation Method 1
the detectors comprises a direct conversion material which produces a pulse-like electric current signal each time a photon enters the material, where the current pulse corresponds to an amount of charge which is indicative of the photon energy
Data Source
AI summary
The invention relates to radiation detector for registering incident photons, comprising (i) detection circuitry (202, 206, 207) configured to provide an electric output signal in response to incident photons, the output signal comprising pulses having an amplitude indicative of energies deposited in the radiation detector by the incident photons, and (ii) an energy estimating circuit (2081, . . . , 208N; 2091, . . . , 209N) configured to detect that the output signal is larger than at least one threshold corresponding to an energy value in order to determine energies of incident photons. The radiation detector further comprises a registration circuit (211) configured to detect incident photons independent of a comparison of the output signal with the at least one threshold. Moreover, the invention relates to a method for detecting photons using the radiation detector.