X-ray Phase Contrast Imaging with Divergent Beam Geometry
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Solution Overview
Problem
Conventional X-ray phase contrast measurements are not feasible in magnifying geometries due to the chaotic pattern of deviated rays, which prevents the accurate measurement of phase shifts and image rendition.
Innovation Solution
A focus-detector arrangement using coherent or quasi-coherent X-radiation with a phase grating and analysis-detector system, where the beam path diverges, allowing for magnifying projective and tomographic phase contrast recordings by optimizing the geometrical relationship between the gratings and detector positions, enabling correct superposition of X-ray wave maxima and minima.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parallel X-ray beams are used for phase contrast measurement, then phase shift measurement is possible, but magnification effect cannot be achieved
Solution Approach 1:
The patent employs dynamic adjustment of the X-ray beam geometry, transitioning from parallel beam configuration to divergent fan beam configuration. This allows the system to adapt between maintaining phase measurement accuracy and achieving magnification effects by controlling the divergence angle and source-to-detector distance ratios
Solution Approach 2:
The patent changes key geometric parameters including beam divergence angle, source-to-object distance, and object-to-detector distance to achieve both phase contrast measurement and magnification. By optimizing these parameters, the system overcomes the limitation of conventional parallel beam geometry
2Adaptability or versatility
If divergent radiation geometry is used to achieve magnification, then magnification effect is obtained, but chaotic ray pattern prevents phase shift measurement
Solution Approach 1:
The system dynamically controls the degree of beam divergence within optimal ranges that maintain both magnification and measurement accuracy. By adjusting divergence angles and geometric relationships during acquisition, the system avoids chaotic ray patterns while achieving desired magnification levels
Solution Approach 2:
The patent optimizes specific geometric parameters including limiting beam divergence angles and maintaining precise source-to-detector distance ratios. These parameter changes ensure that divergent beams produce measurable interference patterns rather than chaotic distributions
3Measurement precision
If phase grating is used to generate interference pattern, then phase shift can be converted to intensity, but complex grating arrangement is required
Solution Approach 1:
The patent extracts and utilizes the natural interference phenomena that occur with divergent X-ray beams and phase objects, reducing the need for complex multi-grating arrangements. By leveraging the inherent wave interference in divergent geometry, the system simplifies the optical path while maintaining phase measurement capability
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 effective magnification of phase contrast recordings, allowing for detailed and high-contrast imaging of the spatial distribution of the refractive index, even in medical computer tomography, with a magnification factor up to 1000 times, overcoming the limitations of conventional methods.
Implementation Method 1
a phase grating which is arranged behind the subject in the beam path of the radiation source and generates an interference pattern of the X-radiation
Implementation Method 2
generates an interference pattern of the X-radiation in a predetermined energy range
Implementation Method 3
The subject causes local phase shifts, which deform the wavefront and therefore locally modify the amplitude, phase and offset of the standing wave field
Implementation Method 4
an analysis-detector system which detects at least the interference pattern generated by the phase grating in respect of its phase shift with position resolution
Data Source
AI summary
A focus-detector arrangement of an X-ray apparatus is disclosed for generating projective or tomographic phase contrast recordings of an observed region of a subject. In at least one embodiment, the arrangement includes a radiation source which emits a coherent or quasi-coherent X-radiation and irradiates the subject, a phase grating which is arranged behind the subject in the beam path of the radiation source and generates an interference pattern of the X-radiation in a predetermined energy range, and an analysis-detector system which detects at least the interference pattern generated by the phase grating in respect of its phase shift with position resolution. Further, the beam path of the X-radiation used diverges in at least one plane between the focus and the detector.