Multi-Camera X-Ray Detector Linearization via Inverse Response Function
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Solution Overview
Problem
Multi-camera flat panel X-Ray detectors face challenges in achieving linear radiometric responses due to non-linearity in optical sensors and lenses, leading to intensity discrepancies and distorted images, which are difficult to calibrate without opening the detector casing, potentially causing contamination.
Innovation Solution
A multi-camera flat panel X-Ray detector system that includes a scintillator, imaging sensors, a light energy measurement unit, and a processing unit to acquire and measure images and energy levels, calculate an inverse response function, and adjust output images using this function, allowing for linearization without opening the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed by opening the detector casing to access optical components, then calibration accuracy is improved, but contamination risk increases
Solution Approach 1:
A light guide is introduced as an intermediary component that transmits light from the scintillator to the imaging sensor through a dedicated optical path. This allows calibration to be performed on the assembled detector without disassembly, as the light guide can be calibrated independently while maintaining the sealed structure of the detector, thus eliminating contamination risk while preserving calibration accuracy
Solution Approach 2:
The detector is segmented into distinct functional modules (scintillator, light guide, imaging sensor, lenses) that can be calibrated independently. The light guide module can be calibrated separately using known light sources before final assembly, or the entire detector can be calibrated in situ without opening the casing, thus maintaining both calibration accuracy and sealed structure
2Ease of manufacture
If multiple optical sensors and lenses are used to replace a single detector chip, then manufacturing cost is reduced, but image quality deteriorates due to intensity discrepancies and non-linearity
Solution Approach 1:
A light guide is introduced as an optical intermediary that uniformly distributes light from the scintillator to multiple imaging sensors. This compensates for variations in sensor and lens characteristics by providing a consistent optical path, thereby reducing intensity discrepancies and non-linearity effects while maintaining the cost advantage of using multiple standard sensors
Solution Approach 2:
The system performs radiometric calibration to determine and apply correction parameters for each imaging sensor and lens combination. By measuring the actual response characteristics and applying compensating transformation parameters, the system corrects intensity discrepancies and non-linearity, thereby improving image quality while maintaining the use of standard, cost-effective sensor components
3Duration of action of stationary object
If calibration is performed regularly in the field, then linearity is maintained throughout the detector lifespan, but system complexity increases
Solution Approach 1:
The detector incorporates self-calibration capabilities where the imaging sensors can be calibrated in situ using built-in or externally accessible calibration targets and known light sources. The system automatically performs calibration measurements and updates correction parameters without requiring complex external equipment or specialized procedures, enabling regular field calibration to maintain linearity throughout the detector lifespan
Solution Approach 2:
Calibration parameters are determined in advance during manufacturing or initial setup, and these pre-determined parameters are stored in the system memory. The system can perform quick validation and adjustment of these pre-established parameters during routine operation, thereby maintaining linearity over time without requiring complex real-time calibration procedures
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
Ensures consistent sensitivity across different radiation doses and maintains image linearity throughout the detector's lifespan by performing a simple, non-invasive linearization process, improving image quality and reducing contamination risks.
Implementation Method 1
a scintillator to convert X-Ray radiation generated by an X-Ray source into detectable radiation
Data Source
AI summary
System and method for linearization of photometric response of an imaging sensor of a multi-camera flat panel X-Ray detector. The linearization includes acquiring by the imaging sensor, during a linearization phase, at least two images related to detectable radiation radiated by a scintillator in response to X-Ray radiation generated by an X-Ray source at a field of view of the imaging sensor, wherein the intensity of the X-Ray radiation generated by the X-Ray source is different for each of the images, measuring by a light energy measurement unit, substantially simultaneously with the acquiring of each of the images, at least two corresponding levels of energy of the detectable radiation, wherein the light energy measurement unit is substantially linear at the range of operation, and calculating an inverse response function to the imaging sensor based on the images and on the corresponding levels of energy.