Optical Sensor Positioning in Cone Beam CT Scanners
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Solution Overview
Problem
Current cone beam computed tomography (CBCT) systems rely on physical motor encoders to determine the movement of x-ray sources and sensors, which can be cumbersome and costly, and do not account for scenarios where the object being scanned is not stationary.
Innovation Solution
A method and system that utilize tracking images from cameras to determine the position and orientation of a sensor system relative to a scanning base without physical motor encoders, using fiducial markers and image analysis algorithms to calculate the movement of the sensor system, even when the object is not fixed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical motor encoders are used to determine sensor system movement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical motor encoders with an optical tracking system using cameras and fiducial markers. The camera system captures images of markers attached to the sensor system, and software algorithms calculate position and orientation from these images, eliminating the need for mechanical encoder components while maintaining measurement precision.
Solution Approach 2:
The patent creates a visual copy of the physical encoder system by using camera images of fiducial markers to represent sensor position. Instead of directly measuring position through mechanical encoders, the system captures optical copies (images) of known marker patterns and computationally determines position from these copies.
2Measurement precision
If physical motor encoders are used to determine sensor system movement, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses inexpensive fiducial markers instead of expensive motor encoders. These markers are simple printed or attached patterns that can be easily manufactured and replaced if needed, significantly reducing the cost of the positioning system while maintaining measurement accuracy through optical tracking.
Solution Approach 2:
The patent substitutes expensive mechanical encoder assemblies with a combination of inexpensive cameras and software processing. The camera system and computational algorithms provide a lower-cost alternative to precision mechanical encoders, reducing manufacturing costs while maintaining measurement capabilities.
3Measurement precision
If traditional encoder systems are used, then rotational axis position is determined accurately, but adaptability to non-stationary objects is reduced
Solution Approach 1:
The patent transitions from a static mechanical encoder system to a dynamic optical tracking system. The camera system can track moving fiducial markers on non-stationary objects, and the software algorithms dynamically calculate position and orientation from sequential images, enabling accurate measurement even when the object being scanned moves during acquisition.
Solution Approach 2:
The patent creates a universal positioning system that can handle both stationary and non-stationary objects using the same camera and marker framework. The system adapts to different object types and movement conditions by processing fiducial marker positions from images, making it versatile for various scanning scenarios without requiring different measurement systems.
Data Source
AI summary
A method for determining the position and/or orientation of at least one sensor system relative to the base structure of a scanning system during scanning of an object, the method includes obtaining one or more tracking images using one or more cameras, where the cameras are in a fixed position with respect to the sensor system; and determining from the one or more tracking images the position and/or orientation of the sensor system relative to the base structure at a given time.