Photon Counting Detector Using Capacitor Accumulation for Noise Reduction
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Solution Overview
Problem
Conventional X-ray CT detectors face challenges in achieving high signal-to-noise ratio and accurate photon counting due to limitations in radiation sensitivity, noise mixture, and high power consumption, especially in large-scale surface detectors.
Innovation Solution
The implementation of a photon counting detector system that includes silicon photomultiplier (SiPM) units with capacitors and a look-up table (LUT) to accumulate and convert electrical signals into digital outputs, reducing noise and radiation sensitivity, and using a CMOS circuit to count outputs directly as digital values without the need for analog-to-digital converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional X-ray detectors are used, then the system can detect X-rays, but the signal-to-noise ratio is low and measurement precision is poor
Solution Approach 1:
The detector is divided into multiple independent pixel units, each with its own capacitor for charge accumulation. This segmentation allows individual charge integration at each pixel, reducing noise from signal mixing and improving photon counting precision through isolated measurement channels.
Solution Approach 2:
Capacitors are introduced as intermediary elements between the X-ray detection elements and the readout circuitry. These capacitors accumulate electrical charge from detected X-ray photons, enabling precise charge integration and signal separation before digital conversion, thereby improving signal-to-noise ratio and measurement accuracy.
2Area of stationary object
If large-scale surface detectors are implemented, then detection area is increased, but power consumption increases and radiation sensitivity decreases
Solution Approach 1:
Each pixel unit in the detector array is equipped with its own capacitor that autonomously accumulates charge from detected photons. This self-service approach at the pixel level eliminates the need for complex external signal processing and analog-to-digital conversion circuits, significantly reducing overall power consumption while maintaining large detector area.
Solution Approach 2:
The patent replaces conventional analog signal processing mechanisms with direct digital signal generation. By using capacitors to accumulate charge and generating digital signals directly, the system eliminates power-hungry analog-to-digital converters and associated processing electronics, reducing power consumption in large-scale detectors.
3Reliability
If analog-to-digital converters are used for each pixel, then signal conversion is achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and removes the analog-to-digital conversion function from each individual pixel circuit. Instead, digital signals are generated directly from the accumulated charge on capacitors through simple readout circuitry. This extraction eliminates complex ADC circuits from each pixel, reducing device complexity and power consumption while maintaining signal conversion accuracy.
Solution Approach 2:
Conventional detectors convert analog signals to digital through complex ADC circuits. This patent inverts the approach by directly generating digital signals from accumulated charge without intermediate analog processing. This inversion simplifies the circuit architecture, reduces power consumption, and eliminates the need for pixel-level ADCs while maintaining reliable signal conversion.
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 enhances the accuracy of photon counting processing, reduces noise interference, and improves the efficiency of X-ray CT image reconstruction by converting analog signals to digital signals directly, thereby improving the signal-to-noise ratio and reducing the complexity and power consumption of the detector system.
Implementation Method 1
The X-ray detection elements detect an X-ray and generate an electrical signal
Implementation Method 2
A capacitor is provided for each of the X-ray detection element, and accumulates an electrical signal generated in each of the X-ray detection element
Data Source
AI summary
A photon counting detector of an embodiment includes X-ray detection elements, a capacitor, and generating circuitry. The X-ray detection elements detect an X-ray and generate an electrical signal. The capacitor is provided for each of the X-ray detection element, and accumulates an electrical signal generated in each of the X-ray detection element. The generating circuitry has low sensitivity to radiation, and generates a digital signal by using an accumulation result of the electrical signal in the capacitors, and reference information that is stored in advance.