Photon Counting Image Detector Signal Leakage Control
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Solution Overview
Problem
Photon counting type image detectors experience signal leakage into surrounding pixels, degrading space resolution and generating noise in X-ray image characteristics due to stochastic signal leakage processes.
Innovation Solution
The implementation of a photon counting type image detector with a semiconductor cell and ASIC layer processing circuits, including charge amplifiers, waveform shaping circuits, comparators, switches, threshold logic circuits, and counters, which adjust gain and offset to classify X-ray photon energy and prevent signal leakage by discriminating between incident and non-incident pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photon counting type image detector is used to count X-ray photons, then the ability to detect and count individual photons is improved, but signal leakage into surrounding pixels occurs which degrades spatial resolution
Solution Approach 1:
The detector is divided into independent pixel units with separate processing circuits for each pixel. Each pixel has its own charge amplifier, waveform shaping circuit, and counter that independently processes signals from its respective sensing element, preventing signal interference between adjacent pixels
Solution Approach 2:
Each pixel is equipped with dedicated signal processing components (charge amplifier, waveform shaping circuit, comparator, counter) that are optimized for local photon detection. The processing circuitry is distributed across the detector array with each pixel having its own complete signal chain, ensuring localized signal processing and preventing cross-pixel contamination
2Quantity of substance
If signal is detected on surrounding pixels due to leakage, then the detection coverage is improved, but noise is generated in image characteristics due to stochastic leakage process
Solution Approach 1:
The patent extracts and removes the leaked signal component from the detection system by implementing energy discrimination. The waveform shaping circuit and comparator identify and exclude signals that do not meet the characteristic energy signature of primary photons, effectively taking out the harmful leaked signal from the measurement
Solution Approach 2:
The signal processing circuit employs feedback mechanisms where the output of the waveform shaping circuit feeds into the comparator, which then controls the counter. The system continuously monitors signal characteristics and adjusts discrimination thresholds to maintain accurate photon counting while rejecting noise and leaked signals
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 solution enhances image resolution by accurately counting X-ray photons and reducing noise, ensuring that signals are proportional to the incident photons without leakage, thereby improving image quality.
Implementation Method 1
a semiconductor cell (X-ray detecting material) and a plurality of processing circuits
Data Source
Figure 1
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Figure 3A~3E
AI summary
A photon counting type image detector has: a semiconductor cell that detects an X-ray photon; a charge amplifier that generates a plurality of electric pulses each being based on an electric charge collected in response to the detected X-ray photon; a comparator that discriminates a peak value of each of the electric pulses; a threshold logic circuit that performs control so as to count none of the peak-discriminated electric pulses corresponding to energy of characteristic X-rays produced in the semiconductor cell; and a counter that counts the discriminated electric pulses as controlled by the threshold logic circuit.