Phase-contrast X-ray Imaging for Local Stoichiometry Estimation
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Solution Overview
Problem
Existing X-ray imaging techniques struggle to directly measure chemical composition of samples, as they either provide indirect measurements or are limited by energy thresholds, making it difficult to image thicker objects and quantify multiple elements simultaneously.
Innovation Solution
A phase-contrast imaging method using an X-ray source and a grid with holes to independently measure the real part (δ) and imaginary part (β) of the complex optical index of a sample, allowing for the estimation of local stoichiometry and chemical composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional X-ray absorption imaging is used, then the imaging process is simple, but it cannot directly measure chemical composition and only provides indirect measurements
Solution Approach 1:
The patent segments the measurement process into two independent components: phase contrast imaging (measuring the real part δ of the optical index) and absorption imaging (measuring the imaginary part β). By using a grid-based phase contrast system combined with absorption measurements, the method independently determines both parts of the complex optical index, enabling direct chemical composition measurement without relying on a single complex system.
Solution Approach 2:
The patent introduces a grid as an intermediary element in the phase contrast imaging path. The grid creates a speckle pattern that, when analyzed through autocorrelation, provides information about the real part of the optical index. This intermediary allows extraction of chemical composition information without directly measuring it, bridging the gap between simple imaging and compositional analysis.
2Measurement precision
If atomic threshold imaging is used to quantify a specific element, then that element can be detected, but no indication is given of other elements in the sample
Solution Approach 1:
The patent employs a multi-functional measurement approach where the same imaging system simultaneously provides information about all elements in the sample. By measuring both the real part (δ) and imaginary part (β) of the optical index across the entire sample, the method enables identification of multiple elements and their relative proportions, not just a single target element. This universal measurement capability eliminates the need for separate measurements for different elements.
3Measurement precision
If low energy X-rays are used to image elements with low atomic number, then those elements can be detected, but slightly thicker objects such as animals or the human body cannot be imaged
Solution Approach 1:
The patent utilizes the energy-dependent behavior of the real part (δ) and imaginary part (β) of the optical index to resolve the contradiction between detecting low atomic number elements and imaging thick objects. By measuring both parameters at appropriate X-ray energies and analyzing their relative magnitudes, the method can identify low atomic number elements even in thick samples, as the ratio and energy dependence of δ and β provide element-specific signatures that penetrate through thicker materials.
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 method enables direct and independent measurement of δ and β, allowing for precise determination of chemical composition without the need for sample destruction, and is applicable across various fields including medicine, agriculture, and energy.
Implementation Method 1
carrying out at least one measurement by illuminating the sample, the X-rays reaching the detector forming a spot for each hole of the grid
Implementation Method 2
phase-contrast imaging method for estimating local stoichiometry of a sample by determining a parameter δ of a real part and an imaginary part β of a complex optical index
Data Source
AI summary
An imaging method for determining a parameter δ of real and imaginary parts of a sample complex optical index; the method using an X-ray source to illuminate the sample, a perforated grating arranged between the sample and the detector, and a signal processing unit; the method performing measurement while illuminating the sample, the X-rays reaching the detector forming a spot for each grating hole; for each measurement and for each grating hole, analysing the grating spot by determining a spot barycenter using a centroid-finding technique, determining an offset of the barycenter relative to a reference barycenter and determining a local phase variation via the offset of the barycenter, determining an amplitude of the X-rays forming the spot and determining a local attenuation relative to a reference amplitude, determining the parameter δ on the basis of the local phase variation, and determining the imaginary part β via the local attenuation.