Dual-Readout Image Sensor for X-Ray Exposure Control
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Solution Overview
Problem
Existing automatic exposure control systems in X-ray imaging face challenges such as ionization chamber shadows, unstable dose rates during X-ray generation, and signal transmission delays, which affect image quality and clinical diagnosis.
Innovation Solution
An automatic exposure control method using a photosensitive element array with first and second photosensitive elements, where readout signals are obtained at different preset times to calculate a dose threshold and control radiation source exposure, eliminating the need for ionization chambers and improving dose rate accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If vacuum ionization chambers are used to detect radiation transmitted through areas of interest, then automatic exposure control function is achieved, but ionization chamber shadows are formed on the image affecting clinical diagnosis
Solution Approach 1:
The patent extracts the harmful ionization chamber component from the detection path by using a dual-readout image sensor that directly detects transmitted X-rays without requiring an ionization chamber in front of the detector. This eliminates the ionization chamber shadow while maintaining automatic exposure control capability through software-based dose calculation from the image sensor signals.
Solution Approach 2:
The image sensor performs multiple functions: it serves as both the primary imaging detector and the radiation dose detector for automatic exposure control. By utilizing the same image sensor for both purposes, the system eliminates the need for separate ionization chambers while achieving automated exposure termination based on real-time dose measurement.
2Measurement precision
If vacuum ionization chambers are installed separately from detectors, then dose detection is achieved, but mobile applications become inconvenient
Solution Approach 1:
The patent merges the dose detection function with the imaging detector by integrating both capabilities into a single image sensor unit. This combination eliminates the need for separate ionization chamber installations, making the system more suitable for mobile and portable X-ray applications while maintaining accurate dose detection through the image sensor's direct measurement capability.
3Reliability
If signal transmission link delay is present in automatic exposure control systems, then real-time performance is affected, but control accuracy is reduced
Solution Approach 1:
The system implements real-time feedback by continuously monitoring the transmitted X-ray signal through the image sensor during exposure and dynamically adjusting exposure parameters based on the measured dose rate. This feedback mechanism compensates for transmission delays by using the most current dose information available to control the exposure termination, maintaining both real-time performance and control accuracy.
4Device complexity
If dose rate deviation during voltage and current climbing period is ignored, then X-ray generation is simplified, but control error increases
Solution Approach 1:
The system performs preliminary measurement of the dose rate during the voltage and current climbing period by continuously monitoring the image sensor signal from the moment X-ray generation begins. This preliminary action captures the dose rate deviation that occurs during the warm-up phase, allowing the system to accurately calculate the total dose and terminate exposure at the correct time, thereby improving dose rate accuracy without significantly increasing device complexity.
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 method enhances dose rate calculation accuracy, reduces ionization chamber shadows, and enables rapid dose detection, improving the automation and accuracy of X-ray exposure control.
Implementation Method 1
providing an image sensor, the image sensor is placed to correspond with the area to be tested, and comprises a photosensitive element array composed of a plurality of photosensitive elements arranged in an array
Data Source
AI summary
The present disclosure provides an automatic exposure control method, including: providing an object to be tested; providing an image sensor, including a photosensitive element array composed of a plurality of photosensitive elements arranged in an array, and the photosensitive element array includes at least a plurality of first photosensitive elements and a plurality of second photosensitive elements; turning on the radiation source, and the first readout signals on the first photosensitive elements are read after exposing the area to be tested for the first preset time; continuing the exposure for the second preset time, turning off the photosensitive elements and reading the second readout signals on the second photosensitive elements; acquiring the preset dose threshold of the area to be tested based on the second and first readout signals, and obtaining the remaining time to reach the preset radiation dose to control the exposure of the radiation source.