Deep Shielding Areas for X-Ray Noise Immunity in Imaging Sensors
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Solution Overview
Problem
Conventional x-ray imaging sensors are prone to noise due to unconverted x-rays, which are not effectively shielded by existing methods, leading to reduced image quality and patient discomfort from increased sensor thickness.
Innovation Solution
The implementation of shielding areas within the sensor that extend deeper than the surface, capturing undesirable charge carriers generated by unconverted x-rays, thereby preventing them from contributing to the image noise, while allowing desired charge carriers to be detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fiber-optic plate is used to shield the sensor from unconverted x-rays, then x-ray noise is reduced, but the sensor thickness increases and light signal is lost
Solution Approach 1:
The patent introduces shielding regions that extend vertically into the bulk region of the sensor, utilizing the depth dimension to block x-ray induced charge carriers. This vertical shielding approach replaces the horizontal fiber-optic plate, achieving noise reduction without increasing the sensor's lateral thickness or compromising patient comfort.
Solution Approach 2:
The shielding regions are strategically positioned in specific areas where x-ray induced charge carriers are generated, rather than using a universal fiber-optic plate across the entire sensor. This localized shielding approach reduces noise in critical areas while maintaining light signal transmission in other regions, avoiding both thickness increase and light loss.
2Object-affected harmful factors
If a fiber-optic plate is used to shield the sensor from unconverted x-rays, then x-ray noise is reduced, but light signal is lost and image quality decreases
Solution Approach 1:
The shielding regions are positioned specifically in areas where x-ray induced charge carriers are generated, allowing light signals to pass through unobstructed in the pixel sensing regions. This selective shielding maintains high image quality by preserving light signal transmission while eliminating only the harmful x-ray noise.
Solution Approach 2:
The sensor is divided into functional regions: pixel regions for light detection and shielding regions for x-ray noise reduction. This segmentation allows each region to perform its specialized function optimally, with shielding regions blocking x-ray induced carriers while pixel regions remain fully sensitive to light signals, thereby maintaining image quality.
3Object-affected harmful factors
If the scintillator converts all x-rays to visible light, then x-ray noise is reduced, but the sensor cannot detect visible light signals effectively
Solution Approach 1:
The sensor structure is segmented into scintillator regions for x-ray conversion and pixel regions for light detection. This segmentation allows the scintillator to convert x-rays to visible light while the pixel regions maintain their silicon-based sensitivity to detect the converted light signals, preserving both x-ray noise reduction and visible light detection capability.
Solution Approach 2:
The scintillator acts as an intermediary that converts x-rays into visible light, which then serves as the actual detection target for the silicon-based pixel regions. This intermediary conversion process allows the sensor to detect x-rays indirectly through visible light, maintaining the natural sensitivity of silicon to visible light signals while eliminating direct x-ray noise.
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 improves x-ray noise immunity and image quality by effectively shielding unwanted x-ray-induced noise, reducing the need for bulky fiber-optic plates and maintaining sensitivity to visible light signals.
Implementation Method 1
a scintillator is disposed on the sensors to convert the energy from the x-rays to visible light. The scintillator is typically composed of gadolinium oxysulphide or cesium iodide
Implementation Method 2
conventional sensors or imaging chips, which generally are fabricated from silicon, are considerably more sensitive to photon energy in the visible spectrum than to x-rays
Data Source
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AI summary
An electronic imaging sensor, which has an improved immunity to noise caused by unwanted x-rays, images an object by collecting charge carriers produced in the sensor when the object is exposed to x-rays. One or more shielding areas are formed proximate the sensor to capture or sweep away any undesirable charge carriers generated by the unwanted x-rays. The shielding areas extend deeper beneath the surface of the sensor than the depth at which the desired charge carriers corresponding to the object being imaged is collected. The shielding areas capture charge carriers formed by the unwanted x-rays, which penetrate into the sensor to a greater depth than the depth at which the desired charge carriers are collected. In this way, the undesirable charge carriers are captured near the region where they are generated and before they migrate towards the surface where they can be collected and manifest as noise in the resulting image of the object.