Ultrasound Transducer and Camera Spatial Registration
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Solution Overview
Problem
Current hand-held sensor systems for medical and environmental applications face challenges in accurate and precise tracking due to limitations in spatial registration, including coarse GPS resolution, drifting INU systems, and the need for direct line of sight in optical marker systems, which are often bulky and expensive.
Innovation Solution
An integrated ultrasound transducer and machine-vision camera system that determines the position and orientation of the transducer in space, allowing for spatially registered scans to reduce artifacts and refine tissue types, with the option to use fiducial markers and flexible tape for improved tracking and 3D modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If GPS is used for tracking, then coverage area is large, but position resolution is coarse
Solution Approach 1:
The tracking system is segmented into multiple components: GPS provides coarse position data over large areas, while local visual markers provide fine position resolution. The system divides the tracking function between global positioning and local refinement, allowing both large coverage and high precision to be achieved simultaneously.
2Ease of operation
If INU system is used for tracking, then portability is improved, but position accuracy drifts over time
Solution Approach 1:
The system uses visual markers as feedback references to correct drift in the INU system. The inertial navigation provides continuous tracking data, and the visual markers provide periodic correction signals that reset accumulated errors, maintaining accuracy over time while preserving portability.
Solution Approach 2:
Visual markers are pre-placed in the environment before tracking begins. This preliminary setup creates a known reference framework that the INU system can use for calibration and drift correction, enabling accurate long-term tracking without requiring continuous external adjustments.
3Measurement precision
If magnetic sensors are used for tracking, then position resolution is high in controlled environments, but position resolution decreases in environments with metallic objects
Solution Approach 1:
Visual markers serve as an intermediary reference system that is unaffected by metallic objects or magnetic interference. Instead of relying directly on magnetic field measurements in challenging environments, the system uses visual markers as a mediator that provides position information independent of electromagnetic interference, maintaining both precision and environmental adaptability.
4Measurement precision
If external CMM camera system is used for tracking, then position accuracy is high, but device complexity and cost increase
Solution Approach 1:
Instead of using expensive external CMM camera systems, the patent uses simple visual markers that can be tracked by standard cameras or image processing. The complex tracking functionality is copied into software algorithms that process images of the markers, replacing expensive hardware with more accessible components while maintaining position accuracy.
5Measurement precision
If optical markers are used for tracking, then position accuracy is high, but continuous line of sight is required
Solution Approach 1:
Multiple visual markers are pre-placed throughout the environment before tracking begins. This preliminary distribution ensures that at least some markers remain visible even when the tracker moves behind obstacles, maintaining continuous tracking without requiring unbroken line of sight to a single marker.
Data Source
AI summary
A shared-housing ultrasound transducer and machine-vision camera system is disclosed for registering the transducer's x, y, z position in space and pitch, yaw, and roll orientation with respect to an object, such as a patient's body. The position and orientation are correlated with transducer scan data, and scans of the same region of the object are compared in order to reduce ultrasound artifacts and speckles. The system can be extended to interoperative gamma probes or other non-contact sensor probes and medical instruments. Methods are disclosed for computer or remote guiding of a sensor probe or instrument with respect to saved positions and orientations of the sensor probe.