X-ray Baggage Scanner Cross-Calibration Transfer Function
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Solution Overview
Problem
Existing scanning technologies face challenges in achieving precise material identification due to variations in apparatus conditions, leading to inadequate data transfer between instruments and limited tolerance for differentiating materials with closely related characteristics, especially in time-sensitive applications like airport security.
Innovation Solution
A method of relative calibration is implemented, where a transfer function is generated to adjust emergent intensity data from a reference database to match specific apparatus conditions, allowing for the creation of a dynamic dataset that can be used across various apparatus conditions, ensuring accurate material identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reference data is collected on one instrument and transferred to another, then data transfer between instruments is achieved, but measurement precision deteriorates due to apparatus condition variations
Solution Approach 1:
The patent introduces a transfer function as an intermediary mathematical model that maps reference data from one instrument to another. This transfer function acts as a mediator that accounts for apparatus condition variations, allowing data to be transferred between instruments while maintaining measurement precision by compensating for instrumental differences through the transformation process
Solution Approach 2:
The patent transforms reference data by applying parameter changes through a transfer function that adjusts intensity values based on the relationship between reference and target apparatus conditions. This parameter transformation allows the same physical quantity to be expressed in terms suitable for different instruments, resolving the contradiction between data transferability and measurement precision
2Measurement precision
If a bespoke reference database is generated for each apparatus, then measurement precision is improved, but productivity deteriorates due to time-consuming calibration
Solution Approach 1:
The patent performs preliminary generation of a transfer function using readily available reference data and current apparatus measurements before actual material identification is needed. This preliminary action creates a calibrated transformation model in advance, so that when materials need to be identified, the system can quickly apply the pre-established transfer function without time-consuming calibration, thus improving productivity while maintaining precision
Solution Approach 2:
The patent creates a transformed copy of the reference database that is adapted to the current apparatus conditions through the transfer function. Instead of generating entirely new reference data from scratch, the system copies and transforms existing reference data, significantly reducing calibration time while maintaining the precision needed for accurate material identification
3Device complexity
If standard processes are used to reduce variations between instruments, then device complexity is reduced, but measurement precision deteriorates due to inadequate tolerance for closely related materials
Solution Approach 1:
The patent applies parameter changes through a transfer function that specifically transforms intensity values to account for apparatus condition variations. This mathematical transformation approach maintains relatively simple calibration processes while significantly improving the precision needed to differentiate materials with closely related characteristics, as the transfer function can precisely adjust for instrumental differences without requiring complex 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
This approach enables the creation of a dynamic reference database that can be easily transferred and calibrated to different apparatus conditions, improving the precision and efficiency of material identification, even across varying operational parameters, thus addressing the limitations of existing technologies.
Implementation Method 1
The interaction of high energy ionising radiation with an object is the subject of a number of physical mechanism including various modes of absorption
Implementation Method 2
The interaction of high energy ionising radiation with an object is the subject of a number of physical mechanism including various modes of absorption, diffraction, elastic and inelastic scattering
Implementation Method 3
measured using an energy selective detector such as cadmium telluride or germanium
Data Source
Figure 1~5
Figure 2
Figure 3a~3
AI summary
To check the content of for example baggage containers at security checkpoints an X-ray system determines the X-ray transmission spectrum of the container and compares the spectrum with spectra of known contraband materials in a reference database. Slight variations between different X-ray systems require the reference database to be adapted to each individual X-ray system. According to the invention two X-ray systems A and B are cross - calibrated using a step wedge, which yields a transfer function for conversion of measured data from system A to system B. This transfer function is used to transfer the reference database of system A to system B.