CT Gantry Vibration Detection Using Balance Sensors
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Solution Overview
Problem
Computed tomography (CT) scanners face challenges in detecting higher order vibrations that occur after installation, which can lead to poor image quality due to reliance on imbalance measurements alone, as external laboratory-type analyzers are costly and not suitable for field service, and do not account for factors like floor stiffness and gantry anchoring.
Innovation Solution
Implementing on-board balance sensors to measure gantry vibrations by sampling data during rotation, deconvolving digitized signals in the frequency domain, and extracting dominant harmonic frequency responses to determine vibration levels, allowing for real-time detection and identification of vibration causes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external laboratory-type analyzers are used to measure gantry vibration, then measurement precision is improved, but device complexity and cost increase, and ease of operation deteriorates due to required training and suitability only for factory settings
Solution Approach 1:
The CT scanner system performs vibration measurement and analysis using its own built-in balance sensors and processing circuitry, eliminating the need for external laboratory equipment. The system self-diagnoses gantry vibration issues using internally available resources including the radiation source, detectors, and balance sensors that are already part of the CT scanner assembly.
Solution Approach 2:
The patent introduces a vibration analyzer as an intermediary component that processes signals from balance sensors to determine gantry vibration levels. This intermediary function can be implemented using existing CT scanner components or as a simplified integrated module, bridging the gap between raw sensor data and diagnostic conclusions without requiring external laboratory equipment.
2Device complexity
If imbalance measurements alone are used to detect gantry vibration, then device complexity is reduced, but measurement precision deteriorates because higher order vibrations occurring more than once per rotation are not detected
Solution Approach 1:
The vibration analysis process is segmented into multiple components: balance sensors measure vibration, signal processing separates different frequency components, and harmonic analysis identifies specific vibration patterns. This segmentation allows the system to handle complex vibration signatures by breaking them down into manageable analytical steps, enabling detection of higher order vibrations without overwhelming complexity.
Solution Approach 2:
The system transitions from measuring only imbalance (one-dimensional measurement) to measuring vibration across multiple frequency dimensions. By analyzing signals at different rotational frequencies and harmonics, the system gains the ability to detect higher order vibrations that occur more than once per rotation, adding frequency dimensionality to the measurement approach.
3Ease of operation
If on-board balance sensors are used to measure gantry vibration, then ease of operation is improved for field service, but measurement precision may be compromised compared to external laboratory equipment
Solution Approach 1:
The balance sensors and processing circuitry in the CT scanner are designed to serve multiple functions: they measure imbalance during manufacturing, detect higher order vibrations during operation, and provide diagnostic information for maintenance. This multi-functionality allows the same on-board components to replace external laboratory equipment for various vibration analysis tasks, achieving both ease of operation and sufficient measurement precision for field service.
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
Enables the detection of gantry vibrations that may cause image artifacts, allowing for timely service and improving image quality without the need for external hardware or costly analyzers, by using on-board sensors to measure and analyze vibrations across various rotation speeds.
Implementation Method 1
measuring a vibration level of a rotatable gantry of the CT system with a balance sensor coupled to a stationary housing of the CT system
Data Source
AI summary
Methods and systems are provided for measuring vibrations in an imaging system. In one embodiment, a method for a computed tomography (CT) system includes measuring a vibration level of a rotatable gantry of the CT system with a balance sensor coupled to a stationary housing of the CT system and outputting a notification indicating potential image artifacts based on the vibration level exceeding a vibration threshold.