X-ray Detection Device Subpixel Architecture for High Sampling Rate
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Solution Overview
Problem
Current X-ray detection systems face limitations in increasing sampling rate and spatial resolution without increasing exposure dose to the subject, as the sensitivity of photodiodes is limited by parasitic capacitance, requiring longer detection periods and potentially higher X-ray doses.
Innovation Solution
The system employs a detection device with subpixels that perform photoelectric conversion and AD conversion, allowing for the generation of pixel signals by adding up outputs from multiple subpixels, enabling improved sampling rates and spatial resolution without increasing exposure dose by using a scintillator, detection unit, and output unit that combines signals from subpixels with different exposure periods and energy discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the detection period is shortened to increase sampling rate, then productivity is improved, but measurement precision deteriorates due to PD sensitivity limits
Solution Approach 1:
Each pixel is divided into multiple subpixels (e.g., 2x2=4 subpixels per pixel). Each subpixel independently performs photoelectric conversion and AD conversion, allowing parallel signal processing. This segmentation enables the system to achieve high sampling rates while maintaining precision by combining multiple short-duration signals.
Solution Approach 2:
Outputs from multiple subpixels are added together to generate the final pixel signal. By merging signals from multiple subpixels that each captured X-rays during the short detection period, the system achieves both high sampling rate (short detection period) and high measurement precision (combined signal strength).
2Measurement precision
If X-ray radiation dose is increased to improve detection sensitivity, then measurement precision is improved, but object-affected harmful factors increase
Solution Approach 1:
Dividing each pixel into multiple subpixels allows the system to achieve high detection sensitivity through signal combination rather than increasing X-ray dose. Each subpixel accumulates signal during the same exposure period, and their combined output provides enhanced sensitivity without additional radiation exposure to the subject.
Solution Approach 2:
The patent replaces the traditional approach of increasing physical X-ray exposure to improve sensitivity with an electronic signal processing approach. By using multiple subpixels and combining their outputs through AD conversion and addition, the system achieves high sensitivity through electronic means rather than increasing mechanical/radiation exposure.
3Measurement precision
If the number of pixels is increased to improve spatial resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Multiple subpixels within each pixel share common circuitry including AD conversion units and signal processing paths. This merging of functional elements across subpixels reduces the overall device complexity compared to having completely independent circuits for each subpixel, while still achieving high spatial resolution through the array of pixels.
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 sampling rate and spatial resolution while maintaining a stable exposure dose, allowing for high-speed and sensitive X-ray detection with reduced radiation exposure.
Implementation Method 1
a scintillator adapted to generate scintillation light in response to incident X-rays
Implementation Method 2
a plurality of subpixels adapted to perform photoelectric conversion in response to the scintillation light
Data Source
AI summary
The X-ray detection device according to an aspect of the present disclosure includes a scintillator that generates scintillation light in response to incident X-rays; a detection unit including a plurality of pixels each generating a pixel signal in response to the scintillation light incident thereon; and an output unit that generates X-ray two-dimensional projection data by using the pixel signals of the pixels. A pixel of the detection unit includes a plurality of subpixels that performs photoelectric conversion in response to the scintillation light; an AD conversion unit that applies AD conversion to outputs of the subpixels; and an adder that generates the pixel signal corresponding to the pixel by adding up outputs of the plurality of subpixels after the AD conversion. The present disclosure is applicable to an X-ray CT device and an X-ray FPD device.