Radiation Detector Automatic Exposure Control
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Solution Overview
Problem
Existing radiation detectors face challenges in maintaining consistent image quality and reducing radiation dose variations across different object sizes, particularly in medical radiography, due to inadequate automatic exposure control mechanisms.
Innovation Solution
A method and apparatus that determine radiation doses received by a subset of pixels in a radiation detector, adjust exposure based on statistical criteria, and form images using another set of pixels, where the first set is distributed among chips, and a processor controls the radiation source to stop emission when certain dose criteria are met, ensuring consistent exposure and image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a physically thin radiation ionization chamber is used as AEC device, then radiation exposure can be adjusted, but image quality consistency and radiation dose control for different object sizes deteriorate
Solution Approach 1:
The detector array is divided into multiple independently controllable detector elements arranged in columns. Each column can be independently activated or deactivated based on the size and attenuation characteristics of the object being imaged. This segmentation allows the system to adapt exposure parameters to different object sizes while maintaining consistent image quality across varying anatomical cross-sections.
Solution Approach 2:
The system dynamically adjusts the number of active detector columns based on real-time assessment of object attenuation properties. By varying the active detector configuration during exposure, the system optimizes radiation dose delivery and image quality for each specific imaging scenario, rather than using fixed exposure parameters.
2Reliability
If radiation exposure is increased to ensure adequate signal for all object sizes, then image quality improves, but radiation dose variation across different sized objects increases
Solution Approach 1:
Different regions of the detector array are selectively activated based on the local attenuation requirements imposed by the object being imaged. Objects with higher attenuation in certain regions trigger activation of corresponding detector columns, while regions with lower attenuation use fewer active detectors. This local adaptation ensures adequate signal quality where needed while minimizing unnecessary radiation exposure in other regions.
Solution Approach 2:
The system changes operational parameters (number of active detector columns) based on the measured attenuation characteristics of different object sizes. By dynamically adjusting this parameter, the system optimizes the balance between signal quality and radiation dose for each specific imaging scenario, reducing dose variation across different patient sizes.
3Extent of automation
If a subset of pixels is used for exposure control, then automatic exposure adjustment is achieved, but the complexity of pixel distribution and dose calculation increases
Solution Approach 1:
The detector array is organized into discrete columns that can be independently controlled. This column-based segmentation simplifies the management of pixel subsets by providing a natural hierarchical structure - instead of managing individual pixels, the system manages columns of pixels as unified units. This reduces the computational complexity of dose calculation and control logic.
Solution Approach 2:
The same detector elements serve dual purposes: they function as both imaging pixels and exposure control pixels. By using detector columns for both image formation and exposure monitoring, the system eliminates the need for separate dedicated control sensors, thereby reducing overall system complexity while maintaining automated exposure control capability.
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 effectively reduces radiation dose variations and maintains consistent image quality by automatically adjusting exposure based on statistical characteristics of radiation doses, enhancing the precision and reliability of radiation detection systems.
Implementation Method 1
a radiation detector of this type may have a semiconductor layer that absorbs the radiation and generate charge carriers (e.g., electrons and holes) and circuitry for detecting the charge carriers
Implementation Method 2
AEC device (e.g., a physically thin radiation ionization chamber) may be positioned between a radiation source (e.g., X-ray source) and a radiation detector
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Disclosed herein is a method comprising: determining doses of radiation received by a first set of pixels of a radiation detector; determining that the doses satisfy a criterion; adjusting exposure of the radiation detector to the radiation in response to the doses satisfying the criterion; and forming an image based on radiation received by a second set of pixels of the radiation detector.