Focal Spot Motion Correction via Virtual Focal Spot Alignment
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Solution Overview
Problem
Imaging systems, such as CT scanners, face challenges in maintaining accurate focal spot alignment due to thermal expansion and mechanical vibrations, leading to focal spot drift and reduced image quality.
Innovation Solution
The implementation of a system with collimators aligned to a virtual focal spot, allowing for focal spot tracking and correction, which involves defocusing end collimators to create a reference channel less sensitive to focal spot motion, enabling accurate measurement and normalization of detector gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source is aligned at a single temperature (e.g., ambient temperature), then the alignment is stable and easy to maintain, but the focal spot position shifts during operation due to thermal expansion, causing aliasing and reduced image quality
Solution Approach 1:
The patent applies parameter changes by aligning the source at multiple temperatures (e.g., ambient temperature and operating temperature) rather than a single temperature. This allows the system to account for thermal expansion effects and maintain focal spot position accuracy across different operational conditions, resolving the contradiction between alignment stability and position accuracy.
2Manufacturing precision
If perfect mechanical alignment of the focal spot is achieved, then image quality would be optimal, but perfect alignment is difficult or impossible to achieve and maintain in commercial and clinical settings
Solution Approach 1:
The patent employs feedback mechanisms by measuring the focal spot position at multiple temperatures and using this information to correct for thermal drift and mechanical misalignment. This feedback approach enables the system to achieve and maintain optimal alignment without requiring perfect mechanical precision, thereby reducing device complexity while preserving image quality.
3Ease of operation
If the focal spot position is allowed to drift due to thermal expansion and mechanical vibrations, then the system operation is simpler, but this causes aliasing and reduced image quality
Solution Approach 1:
The patent applies preliminary action by pre-aligning the source at multiple temperatures (ambient and operating temperatures) before actual imaging operations. This preliminary multi-temperature alignment process establishes a comprehensive reference framework that compensates for thermal drift and mechanical vibrations during operation, maintaining image quality without complicating the actual imaging process.
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 effectively corrects focal spot motion-induced errors, improving spatial resolution and geometric sharpness by providing a linear relationship for focal spot position calibration, thus enhancing image quality.
Implementation Method 1
A plurality of collimators are positioned between the object and the plurality of radiation detectors. At least one collimator at a first end of the plurality of collimators and at least one collimator at second end of the plurality of collimators are aligned to a second focal spot different than the first focal spot location and having a different location.
Data Source
AI summary
Systems and methods for focal spot motion correction are provided. One system includes a radiation source configured to project radiation from a first focal spot onto an object and a plurality of radiation detectors disposed around at least a portion of the object. The plurality of radiation detectors measure received radiation along a path projected from the first focal spot to the plurality of detectors. The imaging system further includes an imaging region from which the detectors provide image information for image reconstruction and a plurality of collimators positioned between the object and the plurality of radiation detectors. At least one collimator at a first end of the plurality of collimators and at least one collimator at second end of the plurality of collimators are aligned to a second focal spot different than the first focal spot and having a different location.