Computed Tomography Focal Spot Control for Variable-Current Scans
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Solution Overview
Problem
Existing CT systems face issues with focal spot sizing, resulting in inconsistent spatial resolution and artifacts in reconstructed images due to fixed focal spot sizes during mA modulated scans, which do not account for varying current levels across views.
Innovation Solution
A CT system with an X-ray tube and controller that dynamically adjusts focal spot size based on current levels during each view, selecting the appropriate focal spot size for each view to enhance spatial resolution and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the smallest available focal spot is selected to support the maximum instantaneous tube power, then spatial resolution is high for views at the highest prescribed current, but spatial resolution is lower for views at lower prescribed currents
Solution Approach 1:
The patent applies dynamics by making the focal spot size changeable during the CT scan exposure. The system dynamically adjusts the focal spot size based on the prescribed current level for each view, transitioning from a fixed focal spot size to a variable one. This allows the focal spot size to adapt to different current requirements, improving spatial resolution for low current views while maintaining adequate resolution for high current views.
Solution Approach 2:
The patent changes the focal spot size parameter according to the prescribed current level. By modifying this critical parameter dynamically during the scan, the system optimizes image quality for each view. The focal spot size is adjusted to match the current requirements, thereby resolving the contradiction between maintaining high spatial resolution and adapting to varying current levels.
2Power
If a larger focal spot is used to support higher current, then tube power capacity is increased, but spatial resolution of reconstructed images is reduced
Solution Approach 1:
The system dynamically selects the appropriate focal spot size based on the prescribed current for each view. When high current is required, a larger focal spot is selected to support the tube power capacity. When lower current is used, a smaller focal spot is selected to maintain high spatial resolution. This dynamic adaptation resolves the contradiction between power capacity and spatial resolution.
Solution Approach 2:
The focal spot size parameter is changed according to the prescribed current level and tube power requirements. By adjusting this parameter dynamically, the system achieves optimal balance between power capacity and spatial resolution for each view, rather than being constrained by a fixed focal spot size.
3Device complexity
If the focal spot size is fixed throughout the exposure, then device complexity is reduced, but image quality consistency across varying current ranges is compromised
Solution Approach 1:
The patent introduces dynamic focal spot size control during the exposure, transitioning from a static to a dynamic system. The focal spot size is adjusted based on the prescribed current level for each view, which improves image quality consistency across varying current ranges. The system manages this increased complexity through automated control algorithms that select appropriate focal spot sizes based on current requirements.
Solution Approach 2:
The focal spot size parameter is dynamically changed according to the prescribed current level, improving image quality consistency. The system manages the complexity of multiple focal spot sizes through automated selection based on current requirements, thereby achieving reliable image quality across different current ranges without excessive manual intervention.
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 improves overall spatial resolution and image quality by aligning focal spot size with current levels, reducing artifacts and optimizing image quality across varying current ranges.
Implementation Method 1
the focal spot is created by focusing the electron beam using focusing electrodes and/or magnets
Implementation Method 2
the focal spot is created by focusing the electron beam using focusing electrodes and/or magnets
Implementation Method 3
A fan-shaped or cone-shaped beam of X-rays produced by electrons colliding with the target
Implementation Method 4
After being attenuated by the object, the X-rays impinge upon an array of radiation detectors
Data Source
AI summary
Methods and systems are provided for increasing a quality of computed tomography (CT) images. In one embodiment, a CT system comprises an X-ray tube and an X-ray controller including one or more processors having executable instructions stored in a non-transitory memory of the CT system that, when executed, cause the one or more processors to, during a first view of a CT scan of an object, focus an electron beam at a first focal spot on a target of the X-ray tube, the first focal spot of a first size; during a second view of the CT scan, focus the electron beam at a second focal spot on the target, the second focal spot of a second size different from the first size; and reconstruct an image of the object from projection data including the first view and the second view.