Photon Detector Calibration via Moving Absorption Filter
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Solution Overview
Problem
Photon counting detector calibration requires high homogeneity in K-edge filters, which is difficult to achieve, leading to image artifacts due to thickness variations and inclusions, making it challenging to produce homogeneous samples of materials with high atomic numbers.
Innovation Solution
A method involving an absorption filter assembly with translation means to move the absorption filter through the photon beam, allowing for calibration of detector pixels with reduced dependence on filter homogeneity, using an absorption material with a K-edge corresponding to the photon energy, and manufacturing at lower costs with more reliable results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high homogeneity K-edge filters are used for calibration, then measurement precision is improved, but manufacturing precision deteriorates due to difficulty in producing homogeneous samples
Solution Approach 1:
The filter is made movable relative to the photon beam through translation means, allowing dynamic positioning. This enables the system to average out inhomogeneities by moving the filter through different positions, thereby achieving precise calibration without requiring the filter to be perfectly homogeneous in its initial state
Solution Approach 2:
The system changes the spatial parameter of the filter position during calibration. By translating the filter to different positions across the beam profile and combining measurements, the system transforms a static homogeneity requirement into a dynamic measurement process that tolerates filter inhomogeneities
2Reliability
If high homogeneity filters are used, then image quality is improved, but device complexity increases due to difficulty in production
Solution Approach 1:
The filter assembly incorporates translation means that enable the filter to be moved dynamically during calibration. This dynamic capability allows the use of simpler, easier-to-manufacture filters while maintaining image quality through positional averaging
Solution Approach 2:
The system enables the use of less expensive filters with lower homogeneity requirements. By moving the filter through multiple positions and combining measurements, the system achieves accurate calibration without requiring expensive, highly homogeneous filters
3Ease of manufacture
If the filter is moved through the beam, then ease of manufacture is improved, but device complexity increases due to addition of translation means
Solution Approach 1:
The filter assembly includes translation means that enable the filter to be moved through different positions relative to the photon beam. This dynamic positioning system allows the use of easier-to-manufacture filters while maintaining calibration accuracy through positional variation
Solution Approach 2:
The translation means serve multiple functions: they enable the filter to be positioned at different locations for calibration, allow averaging of inhomogeneities, and provide flexibility in the calibration process. This multi-functionality justifies the added complexity by enabling easier filter manufacturing
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 reduces the need for high homogeneity in absorption filters, enabling more cost-effective production and reliable calibration of detector pixels, minimizing image artifacts by averaging out inhomogeneities and extending filter lifetime through reduced exposure to photons.
Implementation Method 1
The absorption filter comprises an absorption material with a K-edge that corresponds with an energy of the photons in the photon beam
Data Source
AI summary
The present invention discloses a method to calibrate a photon counting detector (3). An absorption filter (7) is moved transversely through a photon beam (8) emitted towards the detector (3) to average out the effect of inhomogeneties of the absorption filter (7). The invention also relates to an absorption filter assembly and an imaging device (1) comprising such an absorption filter assembly.