X-ray CT Grating Interferometer Period Inversion
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Solution Overview
Problem
Existing X-ray CT systems for phase contrast and dark field imaging face challenges in practical operation due to high technical requirements and costs associated with small grating periods, particularly the third grating structure, which requires highly absorbent materials like gold and complex manufacturing.
Innovation Solution
The system rearranges grating structures to meet Talbot conditions, where the third grating period is larger than the second, and the first grating period, allowing for a simpler structure with reduced material requirements, using lead instead of gold and enabling a larger gantry opening for examining larger objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the third grating structure uses a small grating period with highly absorbent material like gold, then the measurement precision and phase sensitivity are improved, but the manufacturing complexity and costs increase significantly
Solution Approach 1:
The patent applies parameter changes by inverting the grating period sequence - making the third grating period larger than the first and second grating periods. This fundamentally changes the design parameters from conventional approaches where periods decrease sequentially. By increasing the third grating period, the patent reduces manufacturing complexity and material costs while maintaining phase sensitivity through the Talbot condition relationships between the gratings
Solution Approach 2:
The patent implements inversion by reversing the conventional grating period arrangement. Instead of p0 > p1 > p2, the patent uses p0 < p1 < p2, where the third grating has the largest period. This inverted approach eliminates the need for highly absorbent materials like gold in the third grating, replacing them with less expensive materials like lead, thereby reducing manufacturing complexity while preserving measurement precision
2Measurement precision
If the third grating structure uses a small grating period with high absorption material, then the phase detection capability is improved, but the costs and material requirements increase
Solution Approach 1:
The patent changes the material parameter by selecting lead instead of gold for the third grating structure. This parameter change is enabled by the inverted grating period design, where the larger third period allows less absorbent material to be used while maintaining sufficient phase detection capability through the interferometric measurement principle
Solution Approach 2:
The patent applies this principle by replacing expensive gold material with cheaper lead material in the third grating structure. The inverted grating period design allows this substitution without compromising measurement precision, effectively using a cheaper material to achieve the same functional outcome
3Measurement precision
If the first and second grating structures use small grating periods, then the phase contrast resolution is improved, but the gantry opening size is reduced
Solution Approach 1:
The patent resolves this contradiction by optimizing the spatial arrangement and distance relationships between the three grating structures along the beam path. By carefully selecting the distances between gratings to satisfy Talbot conditions, the patent achieves both high resolution (through appropriate grating periods) and large gantry opening (through optimized spacing), effectively utilizing the third dimension of space along the X-ray path
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 configuration reduces manufacturing effort and costs, allows for easier implementation of the first grating structure with an anode or electron beam, and maintains phase sensitivity while using less absorbent material, enabling efficient X-ray phase contrast and dark field imaging.
Implementation Method 1
a second grating structure, which, as a phase grating, causes a partial phase shift of a passing X-radiation
Implementation Method 2
a third grating structure with a third Grating period, with the help of which relative phase shifts of adjacent X-rays and / or their scattering components are detected
Implementation Method 3
the three grating structures fulfilling the Talbot conditions with regard to their distances from one another
Data Source
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AI summary
The invention relates to an X-ray CT system (C1) for X-ray phase-contrast and/or X-ray dark-field imaging with a grating interferometer comprising: a first grating structure (G0) having a plurality of strip-shaped and parallel X-ray emission maxima and minima having a first grating period (p0), a second strip-shaped grating structure (G1) which, as a phase grating, causes a partial phase shift of a passing X-ray and has a second grating period (p1), a third strip-shaped grating structure (G2) with a third grating period (p2) with which a relative phase shift of adjacent X-rays (S1, S2) and/or their scattering components are detected, and a device for determining the phase between adjacent X-rays and/or the spatial intensity profile per detector element perpendicular to the strips of the grating structures.The invention is characterized in that the third lattice structure (G2) has a lattice period (p2) that is larger than the lattice period (p0) of the first lattice structure (G0).