X-ray CT System Phase Contrast Grating Displacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional X-ray CT systems face challenges in producing both phase contrast and absorption images efficiently, as they require coherent radiation sources, leading to high radiation doses for patients and are technically demanding due to the need for high-contrast, short-period X-ray optical gratings, which are not suitable for regular use in absorption CT.
Innovation Solution
The X-ray CT system incorporates a gantry with a stationary stator and a rotating rotor, featuring X-ray optical gratings that can be displaced relative to the rotor, allowing for flexible use in both absorption and phase contrast imaging with minimized radiation burden. This design includes a diaphragm to adapt the beam cone and uses quasi-coherent X-radiation sources for efficient examinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small focus X-ray source is used to achieve spatial coherence for phase contrast imaging, then phase contrast measurement capability is improved, but the dose rate becomes insufficient for examining relatively large objects
Solution Approach 1:
The patent segments the imaging process into two distinct operational modes: phase contrast imaging mode (using small focus settings for spatial coherence) and general CT imaging mode (using large focus settings for adequate dose rate). This segmentation allows each mode to operate with optimized parameters without compromising the other, resolving the contradiction between measurement precision and power output.
Solution Approach 2:
The patent implements dynamic switching between different focus settings of the X-ray source. The focus size can be adjusted in real-time depending on the imaging requirement: small focus for phase contrast measurements requiring spatial coherence, and large focus for general CT examinations requiring higher dose rates. This dynamic adaptability resolves the contradiction by allowing the system to optimize for either precision or power as needed.
2Measurement precision
If synchrotron radiation is used as a coherent radiation source, then phase contrast imaging capability is improved, but the construction cost becomes very expensive and widespread application is impossible
Solution Approach 1:
The patent replaces the expensive, complex synchrotron radiation source with a conventional, inexpensive X-ray tube that can be disposed of or replaced easily. While the X-ray tube produces incoherent radiation requiring additional optical components (gratings) to achieve phase contrast, the overall system cost is dramatically reduced, enabling widespread clinical application while maintaining phase contrast imaging capability.
Solution Approach 2:
The patent introduces X-ray optical gratings as intermediary components that convert incoherent X-ray radiation from a conventional source into coherent beams suitable for phase contrast imaging. These gratings act as mediators that enable phase contrast capability without requiring a synchrotron, thus resolving the contradiction between measurement precision and device complexity/cost.
3Measurement precision
If X-ray optical gratings with high contrast ratio and short period are permanently installed in the beam path, then phase contrast measurement capability is improved, but the radiation burden on the patient increases strongly
Solution Approach 1:
The patent implements dynamic positioning of the X-ray optical gratings, allowing them to be moved into the beam path only when phase contrast imaging is required and retracted when not needed. This dynamic control enables the system to minimize radiation burden by using the gratings only selectively, rather than permanently, thus resolving the contradiction between measurement precision and harmful radiation exposure.
Solution Approach 2:
The patent applies the X-ray optical gratings locally and selectively only in the specific regions and time periods when phase contrast measurement is required, rather than universally and continuously. This localized application reduces the overall radiation burden on patients while maintaining phase contrast capability where and when needed, resolving the contradiction between measurement precision and harmful effects.
4Measurement precision
If the first grating is arranged inside the focus/detector combination directly following the focus, then coherent beam fields are produced, but the alignment requirements become very demanding and device complexity increases
Solution Approach 1:
The patent designs the first grating system to self-align with the X-ray source focus through geometric relationships and mechanical constraints built into the system architecture. The grating positioning is automatically determined by the source-grating-detector geometry, reducing the need for complex manual alignment procedures and specialized expertise, thus resolving the contradiction between measurement precision and device complexity.
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
The system enables the production of high-quality tomographic phase contrast and absorption images with reduced radiation exposure to patients, allowing for flexible operation between absorption and phase contrast measurements while maintaining a low dose commitment.
Implementation Method 1
The slits of the first grating produce a field of individually coherent beams that suffices for producing the interference pattern
Implementation Method 2
The first grating produces an interference pattern that images a moiré pattern on to the detector lying therebehind with the aid of the second grating
Implementation Method 3
an examination object is irradiated by a coherent X-radiation and subsequently guided through a pair of gratings, and the radiant intensity is measured directly after the second grating. The first grating produces an interference pattern that images a moiré pattern on to the detector
Implementation Method 4
tomographic images of an examination object, in particular of a patient, are taken with the aid of absorption measurements of X-rays that penetrate the examination object
Implementation Method 5
the effect of the phase shift upon passage of a beam through an examination object is substantially stronger than the absorption effect of the material penetrated by the radiation
Data Source
AI summary
An X-ray CT system is disclosed for producing tomographic phase contrast and absorption images. In at least one embodiment, the system includes a gantry, including a stationary stator and a first rotor supported on the stator and rotates relative to the stator about a system axis, at least one X-ray source detector system that can rotate about a patient and a system axis and is arranged on the first rotor, and at least one set of X-ray optical gratings for determining phase contrast. According to at least one embodiment, the at least one set of X-ray optical gratings is arranged such that it can be displaced relative to the first rotor of the gantry.