Inverse Geometry X-ray Source Array for Spectral CT
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Solution Overview
Problem
Current spectral CT systems face challenges such as high hardware costs, complex detector production, limited spectral separation, and motion artifacts due to dual-source and dual-layer configurations, as well as low spectral separation and high hardware effort in photon-counting systems.
Innovation Solution
An X-ray examination apparatus with an inverse CT geometry using a plurality of X-ray sources and a control unit that switches sources between different energy spectra, allowing only one source or group to be active at a time, with alternating kV modulation to reduce acquisition time and motion artifacts, and employing distributed X-ray sources and energy-discriminating detectors to minimize hardware costs and improve temporal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual-source CT systems with dissimilar kVp settings are used, then two material components can be unambiguously separated, but high hardware costs occur since two sources and two detectors have to be mounted
Solution Approach 1:
The X-ray source is segmented into multiple discrete electron emitters with independent control, allowing different energy spectra to be generated by different segments. This enables spectral CT functionality without requiring separate dual-source systems, reducing hardware complexity while maintaining material separation capability
Solution Approach 2:
The system dynamically switches between different energy spectra by controlling the timing and intensity of electron emitters in the array. This dynamic modulation allows the system to adapt to different spectral requirements without physical reconfiguration, achieving spectral separation through temporal control rather than static dual-source architecture
2Productivity
If fast dual kVp switching is implemented, then spectral CT capability is achieved, but low spectral separation occurs since strong kV transients are difficult to realize
Solution Approach 1:
By dividing the X-ray source into multiple independently controllable electron emitters, the system can switch between different spectral outputs without requiring transient kV changes. Each emitter can be independently activated with appropriate energy levels, achieving spectral separation through spatial distribution rather than temporal switching transients
Solution Approach 2:
The system changes the energy spectrum parameter by controlling the intensity and timing of electron emitters rather than relying on kV transients. This allows for smooth spectral transitions and stable emission characteristics, achieving both fast switching and good spectral separation by modifying emission parameters rather than voltage transients
3Measurement precision
If photon-counting spectral CT is used, then detection capability is improved, but high hardware effort is required
Solution Approach 1:
The flat-panel detector is designed to serve multiple functions: it detects X-rays from different energy spectra, enables spectral CT imaging, and provides temporal resolution through frame-rate control. This multi-functional approach achieves photon-counting capability without requiring separate specialized detectors for each function, reducing overall hardware effort
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 reduces acquisition time, minimizes motion artifacts, and enhances temporal resolution while reducing hardware costs and complexity, enabling better spectral separation and flexible data acquisition across different energy modes.
Implementation Method 1
a large distributed X-ray source with an array of discrete electron emitters and focal spots
Implementation Method 2
carbon-nanotubes (CNTs), as described, for instance, in Liu, Z. et al., 'Carbon nanotube based microfocus field emission x-ray source for microcomputed tomography'
Implementation Method 3
an X-ray detection unit for detecting X-rays emitted from one or more of said X-ray sources after penetration of an examination area
Data Source
AI summary
The present invention relates to an examination apparatus and a corresponding method to realize a Spectral x-ray imaging device through inverse-geometry CT. The proposed examination apparatus comprises: an X-ray source unit (14) comprising a plurality of X-ray sources (15) for emitting X-rays (24) at a plurality of locations, an X-ray detection unit (18) for detecting X-rays emitted from one or more of said X-ray sources (15) after penetration of an examination area (19) between said X-ray source unit (14) said X-ray detection unit (18) and for generating detection signals, a processing unit (36) for processing the generated detection signals, and—a control unit (26) for controlling said X-ray sources (15) to subsequently, alone or in groups emit X-rays at least two different energy spectra such that in the time interval, during which a particular X-ray source (15a) or said group of X-ray sources (15a,15d, 15g), is switched over to emit X-rays at a different energy spectrum, said particular X-ray source (15a) or said group of X-ray sources (15a, 15d, 15g) is switched off and one or more other X-ray sources (15b, 15c) or groups of X-ray sources (15b, 15e, 15h; 15c, 15f, 15i) are subsequently switched on to emit X-rays.