Virtual Rigid Body Optical Tracking for Surgical Tool Positioning

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Solution Overview

Problem

Conventional optical tracking systems in image-guided surgery face limitations such as the need for a line of sight and size constraints due to the physical size of optical markers, which can hinder accurate tracking of surgical tools, especially in crowded surgical workspaces.

Innovation Solution

A virtual rigid body optical tracking system that projects a light pattern onto a surface, allowing for the detection and reconstruction of a 3D marker, enabling tool tracking without the need for a direct line of sight to the tool and allowing for a larger effective marker size within the field of view of the optical tracker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional optical markers are used for tracking, then tracking accuracy can be achieved, but the size of the marker is limited by the physical constraints of the tool and surgical workspace

Engineering Contradiction:

Improvetracking accuracyVSAvoidmarker size

Core Design Contradiction:

Measurement precisionVSArea of moving object

Solution Approach 1:

The patent creates a virtual copy of the rigid body marker in the form of a light pattern projection. Instead of using a physical marker of limited size, the system projects a scaled-up virtual representation (e.g., 10x larger) onto a surface, allowing the optical tracker to detect a much larger apparent size while the actual physical device remains small. This resolves the contradiction by decoupling the physical marker size from the detectable marker size.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent transitions from a two-dimensional physical marker attached to the tool into a three-dimensional virtual projection space. By projecting the marker pattern onto a surface in the surgical field, the system effectively uses the third dimension (depth/projection distance) to scale up the apparent size of the marker without increasing the physical size of the tool or marker itself.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If optical markers are made larger to improve detection, then detection accuracy improves, but the crowded surgical workspace becomes more constrained

Engineering Contradiction:

Improvedetection accuracyVSAvoidsurgical workspace

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The virtual projection creates a large-detection-area copy of the marker that exists only in optical space, not physical space. The light pattern can be projected to appear very large on the surgical field surface, improving detection accuracy, while the actual physical footprint on the tool remains minimal, thus not constraining the surgical workspace.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent introduces a projection surface (the patient's body or surgical field surface) as an intermediary between the small physical marker and the large detection target. The marker pattern is projected through this intermediary surface, allowing the detection system to track a large virtual image without requiring physical space for a large marker.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If electromagnetic sensors are used for tracking, then line of sight is not required, but accuracy is compromised in the presence of metal tools

Engineering Contradiction:

Improvetracking in metal environmentsVSAvoidtracking accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces electromagnetic sensing with optical sensing. Instead of using EM fields that are distorted by metal, the system uses light projection and optical detection. This substitution allows tracking to proceed without the metal interference problem while maintaining accuracy through the virtual marker projection technique.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides accurate 6-degree-of-freedom tracking with reduced size constraints, enabling more flexible and accurate tool positioning during surgical procedures, comparable to conventional optical tracking systems while overcoming traditional optical tracking limitations.

Implementation Method 1

a virtual rigid body generator for projecting a virtual rigid body, wherein the virtual rigid body forms a pattern of light on a surface

Methodology Applied

Scientific EffectLight projection: Light

Implementation Method 2

an optical detection system for detecting the pattern of light

Methodology Applied

Scientific EffectOptical detection: Photoelectric Effect

Data Source

PatentUS10105186B2Virtual rigid body optical tracking system and method

Publication Date: 2018.10.23 JOHNS HOPKINS UNIVERSITY

AI summary

A virtual rigid body optical tracking system includes a virtual rigid body generator for projecting a virtual rigid body, wherein the virtual rigid body forms a pattern of light on a surface. The virtual rigid body optical tracking system includes an optical detection system for detecting the pattern of light, and a data processing system in communication with the optical detection system. The data processing system is configured to determine a position of the virtual rigid body generator based on the detected pattern of light.