Navigated Surgery Point Acquisition via Coordinate Transformation
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Solution Overview
Problem
In navigated surgery, the accuracy of point acquisition is compromised when the marker array is not securely fixed to the anatomical structure or is far away from the region of interest, leading to inaccuracies in tracking, especially when using surgical instruments with smaller marker geometry and flexible connections.
Innovation Solution
A method that uses a first coordinate transformation to transfer point coordinates from a tracked pointer to a globally fixed camera array coordinate system, and then to a coordinate system attached to the anatomical structure, accounting for transformations of multiple points to improve accuracy and compensate for tracking inaccuracies, while ensuring the anatomical structure remains stable relative to the camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a marker array is fixed to a surgical instrument with flexible connection to the anatomical structure, then the instrument can be positioned and tracked, but tracking accuracy is compromised due to flexibility and distance from the region of interest
Solution Approach 1:
The patent introduces a pointer instrument as an intermediary device that directly contacts the anatomical structure to acquire landmark points, while the marker array remains on the surgical instrument. The coordinate transformation process mediates between the pointer's direct contact accuracy and the instrument's tracked position, combining both data sources to achieve accurate point acquisition despite the flexible connection.
Solution Approach 2:
The patent replaces direct mechanical attachment of the marker array to the anatomical structure with an optical/electronic coordinate transformation system. Instead of rigidly fixing markers to bone, the system uses tracked coordinates from the surgical instrument and transforms them through calculated relationships to determine anatomical landmark positions, substituting mechanical rigidity with computational accuracy.
2Ease of operation
If the marker array is placed far from the region of interest to avoid soft-tissue conflicts, then instrument placement is easier, but point acquisition accuracy decreases
Solution Approach 1:
The pointer instrument serves as an intermediary that bridges the gap between the distant marker array and the region of interest. By having the pointer directly contact and palpate anatomical landmarks while being tracked by the navigation system, the system obtains accurate landmark coordinates independent of the marker array's distance from the surgical site.
Solution Approach 2:
The system separates the functions of tracking (performed by the marker array on the surgical instrument) and landmark acquisition (performed by the pointer contacting anatomical structures). This segmentation allows the marker array to be positioned optimally for instrument tracking while the pointer independently acquires accurate anatomical landmark data through direct contact.
3Object-affected harmful factors
If surgical instruments use smaller marker geometry to avoid conflicts with soft-tissue structures, then soft-tissue interference is reduced, but tracking and point acquisition accuracy are reduced
Solution Approach 1:
The patent substitutes the mechanical tracking of small markers on the surgical instrument with a hybrid system that combines instrument tracking with direct anatomical landmark palpation. The pointer's contact-based landmark acquisition provides accurate anatomical reference points that compensate for the reduced tracking accuracy from small markers, replacing reliance on marker geometry with direct physical measurement.
Solution Approach 2:
The system changes the measurement parameters by using the pointer to directly measure anatomical landmarks in three-dimensional space, rather than relying solely on optical tracking of small markers. This parameter change from optical tracking to direct contact measurement maintains accuracy while allowing small marker geometry on the surgical instrument.
Data Source
Figure 1~2
AI summary
The present invention relates to a method for acquiring the position of points for navigated surgery, the method being constituted to be executed by a computer and comprising the following steps: - acquiring, on the basis of detecting a first tracked device, first point position data for each of at least two points, wherein the first point position data comprise point position information describing the three-dimensional position of the point within a first co-ordinate system assigned to the first tracked device; - acquiring first co-ordinate transformation data for each of at least two points, wherein the first co-ordinate transformation data comprise co-ordinate transformation information describing a transformation of the three-dimensional position of the point from the first co-ordinate system to a second co-ordinate system; - acquiring second co-ordinate transformation data for each of at least two points, wherein the second co-ordinate transformation data comprise co-ordinate transformation information describing a transformation of the three-dimensional position of the point from the second co-ordinate system to a third co-ordinate system assigned to a second tracked device; - determining, on the basis of the first and second co-ordinate transformation data, second point position data for each of at least two points, wherein the second point position data comprise point position information describing the three- dimensional position of the point within the third co-ordinate system; wherein the second point position data of at least one of the at least two points are determined on the basis of the second co-ordinate transformation data of at least one other of the at least two points.