Self-Locating Active Markers for Continuous Surgical Co-Registration
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Solution Overview
Problem
Existing surgical methods face challenges in accurately and continuously co-registering external and internal coordinate systems during navigated, augmented reality, or robotic surgery, with conventional markers being unstable or invasive, leading to inaccuracies and increased surgical time.
Innovation Solution
Self-locating active markers (SLAMs) equipped with ultrasound technology and optional 9-axis accelerometers, which affix to the skin and continuously locate themselves relative to internal anatomy, providing precise co-registration between AR systems and medical imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional skin tags or markers are used for co-registration, then the external coordinate system can be tracked, but the markers move with respect to internal anatomy during the operation causing inaccuracies
Solution Approach 1:
The patent introduces an intermediary mechanism (the marker system with internal reference features) that connects the external tracking space to the internal anatomy. The marker includes both external visible features for tracking and internal reference features that maintain spatial relationship with anatomy, serving as a mediator between the two coordinate systems.
Solution Approach 2:
The patent replaces the mechanical attachment system (skin tags glued to skin surface) with an ultrasound-based self-location system. Instead of relying on mechanical adhesion that moves with skin, the system uses ultrasound transducers to actively determine the marker's position relative to internal anatomy, substituting mechanical coupling with acoustic field-based positioning.
2Measurement precision
If bone clamps are used to attach markers to internal anatomy, then co-registration accuracy improves, but the procedure becomes more invasive and requires larger incisions
Solution Approach 1:
The patent replaces the mechanical bone clamp attachment system with an ultrasound-based self-location system. Instead of mechanically clamping to bone (which requires incisions and exposure), the system uses ultrasound transducers to actively determine position relative to internal anatomy, substituting invasive mechanical attachment with non-invasive acoustic positioning.
Solution Approach 2:
The marker system performs self-location and self-registration using its own integrated ultrasound transducers. The marker autonomously determines its position relative to internal anatomy without requiring external mechanical attachment devices like bone clamps, making the system self-sufficient and non-invasive.
3Loss of information
If intraoperative C-Arm imaging is used to guide surgery, then real-time internal anatomy visualization is achieved, but radiation exposure to patient and staff increases significantly
Solution Approach 1:
The patent replaces the X-ray-based C-Arm imaging system with an ultrasound-based positioning system. Instead of using ionizing radiation (X-rays) to visualize internal anatomy, the system uses ultrasound waves to actively determine the marker's position relative to internal structures, substituting radiographic imaging with acoustic imaging.
Solution Approach 2:
The patent changes the physical parameter used for imaging from ionizing radiation (X-rays) to non-ionizing acoustic waves (ultrasound). This parameter change maintains the ability to obtain real-time positional information while eliminating the harmful radiation effects.
4Loss of information
If multiple C-Arm images are taken during surgery, then anatomical information is updated, but surgical time increases due to technician availability and image processing
Solution Approach 1:
The patent implements continuous real-time tracking using the marker system with ultrasound self-location. Instead of taking discrete C-Arm images at intervals, the system continuously monitors the marker's position relative to internal anatomy, providing ongoing anatomical information without interruption to the surgical flow.
Solution Approach 2:
The marker system autonomously performs its own localization and tracking without requiring external C-Arm imaging or technician intervention. The integrated ultrasound transducers continuously determine position independently, eliminating the need for scheduled imaging sessions and associated delays.
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
SLAMs enhance the precision of co-registration, reducing inaccuracies and invasive procedures, thereby improving surgical accuracy and efficiency by maintaining continuous alignment of external and internal coordinate systems.
Implementation Method 1
Each sensing device includes at least an ultrasound transceiver
Implementation Method 2
utilize a non-invasive probing energy that reflects from internal structures
Implementation Method 3
Each sensing device includes at least an accelerometer
Data Source
AI summary
Self-locating active markers (SLAMs) can locate themselves with respect to patient's internal anatomy and be physically located and visible in an operating room (OR) coordinate space, which can increase precision of co-registration between augmented reality (AR) systems and medical imaging. Each SLAM may include 9-axis accelerometers and ultrasound technology to locate themselves by orientation and distance to internal skeletal and/or soft tissue anatomy. Multiple SLAMS affixed to skin near operative site at a location visible to a surgical navigation system and/or the surgeon's AR Headset during a procedure may report relative distance changes between their location and internal skeletal anatomy in order to maintain surgical navigation system or AR coordinate system co-registration to the imaged internal coordinate systems. Sequential time of flight calculations from ultrasound array alone or in combination with 9-axis accelerometer data may be used.