Grating-Based DPCI Imaging with Continuous Translation
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Solution Overview
Problem
Conventional CT imaging struggles with differentiating pathologic from non-pathologic tissue when tissues have similar absorption cross-sections, leading to poor contrast in applications like mammography and angiography, and existing grating-based DPCI systems face mechanical accuracy challenges due to sub-micron precision requirements during phase stepping.
Innovation Solution
A grating-based DPCI system where at least one of the phase or absorber gratings continuously translates with respect to the other during an integration period, reducing mechanical accuracy demands and enabling synchronization of phase coding and detection, while a signal processor extracts absorption, coherence, and phase components from the detector signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase stepping is performed with discrete steps to extract phase information, then measurement precision of phase shift is improved, but mechanical precision requirements increase to sub-micron accuracy
Solution Approach 1:
The patent applies continuous translation of the absorber grating instead of discrete stepping, transforming the static phase stepping process into a dynamic continuous motion process. This allows phase information extraction through temporal sampling during continuous motion, reducing mechanical positioning precision requirements from sub-micron to millimeter or micrometer level while maintaining measurement accuracy through software-based phase extraction from the continuous signal
Solution Approach 2:
The patent replaces the mechanical precision-dependent discrete stepping system with a continuous translation system combined with temporal sampling and software-based phase extraction. The phase information is obtained through signal processing of the continuous translation data rather than through precise mechanical positioning at discrete steps, substituting mechanical precision requirements with computational analysis
2Measurement precision
If discrete phase stepping is performed with multiple acquisitions, then phase information extraction is improved, but scanning time increases due to KxL acquisitions required
Solution Approach 1:
The patent implements continuous translation of the absorber grating throughout the integration period, eliminating the stop-and-step nature of discrete phase stepping. The useful action of data acquisition continues uninterrupted during grating translation, with phase information extracted from the continuous signal through temporal sampling, thereby reducing total scanning time while maintaining measurement accuracy
Solution Approach 2:
The patent utilizes periodic sampling during the continuous grating translation, where detector signals are sampled at regular intervals corresponding to the grating motion. This periodic sampling captures sufficient phase information across the translation cycle, enabling accurate phase extraction with fewer total acquisitions compared to discrete phase stepping while maintaining measurement precision
3Measurement precision
If sub-micron positioning accuracy is maintained during gantry rotation, then phase measurement accuracy is improved, but mechanical stability becomes difficult to maintain under g force
Solution Approach 1:
The patent transitions from static discrete positioning to dynamic continuous translation during gantry rotation. The continuous motion system is less sensitive to g-force-induced positioning errors because it relies on temporal sampling and software-based phase extraction rather than maintaining precise mechanical positioning against gravitational forces during rotation, thereby improving both measurement accuracy and mechanical reliability
Solution Approach 2:
The patent replaces the mechanically precision-dependent positioning system with a continuous translation system where phase information is extracted through temporal sampling and computational analysis. This substitution reduces reliance on mechanical stability under g-force during gantry rotation, as the phase measurement accuracy depends on temporal sampling consistency rather than spatial positioning precision under gravitational influence
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 enhances image contrast and mechanical stability, allowing for accurate phase differentiation and reduced mechanical precision requirements, making it suitable for high-speed rotating gantries and improving tissue differentiation in CT imaging.
Implementation Method 1
The phase grating 112 acts as a beam splitter and divides an incoming X-ray beam essentially into the two first diffraction orders
Implementation Method 2
The diffracted beams interfere and form, in Talbot distances, linear periodic fringe patterns
Implementation Method 3
The object 114 in the beam path causes a slight refraction for each coherent subset of X-rays, which is proportional to the local phase gradient of the object
Implementation Method 4
The absorber grating 110 acts as a transmission mask for the detector 104 and transforms local fringe positions into signal intensity variations
Implementation Method 5
the geometric magnification factor defined by 1 / (1+d)
Data Source
Figure 1
Figure 2
Figure 2(A)~2(C)
AI summary
An imaging system (200) is configured for grating-based DPCI. The imaging system includes a rotating gantry (204) that rotates around an examination region, a radiation source (208), supported by the rotating gantry, that emits radiation that traverses the examination region, a detector array (212), supported by the rotating gantry, that detects radiation that traverses the examination region, and an interferometer, supported by the rotating gantry, which includes a source grating (214), a phase grating (218), and an absorber grating (220). At least one of the phase grating or the absorber grating continuously translates with respect to the other during an integration period and the detector generates and outputs an electrical signal indicative of the detected radiation, wherein the electrical signal includes an absorption component, a coherence component and a phase component.