Magnetic Tracking Probe With Contact Sensor For CT Registration
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Solution Overview
Problem
Existing medical registration systems for magnetic tracking systems are inaccurate due to imprecise positioning of probes at pre-determined features on a subject's skin, leading to potential depression of the skin or lack of contact, which affects the registration of images with tracking systems.
Innovation Solution
A magnetic tracking system with a probe equipped with a contact sensor, such as an electrode, that measures impedance to verify valid contact with registration points, ensuring accurate registration by confirming impedance within a specific range (20 kΩ - 40 kΩ at 20 kHz), and a magnetic detector to determine positions in a coordinate frame, with a processor verifying valid contact before registering the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a probe is positioned at pre-determined features on the subject's skin for registration, then the registration process can be completed, but the positioning accuracy deteriorates due to skin depression or lack of contact
Solution Approach 1:
The system incorporates a contact sensor that provides real-time feedback on the quality of contact between the probe and registration points. The processor uses this feedback to verify whether the probe is properly contact the skin before accepting registration data, allowing the operator to adjust probe positioning based on quantitative contact quality metrics
Solution Approach 2:
The invention replaces manual visual assessment of probe contact with an automated sensor-based detection system. The contact sensor and processor automatically verify contact quality by measuring electrical properties, eliminating reliance on operator judgment and providing objective, quantitative contact verification
2Reliability
If the probe is pushed against the subject to ensure contact, then contact reliability improves, but measurement precision deteriorates due to skin depression
Solution Approach 1:
The contact sensor provides quantitative feedback about contact quality, allowing the system to distinguish between proper contact and excessive pressure. The processor uses this feedback to accept or reject registration points based on whether contact quality falls within an optimal range, preventing skin depression while ensuring reliable contact
Solution Approach 2:
The system measures and utilizes electrical impedance as a parameter to optimize contact quality. By monitoring impedance values, the system can determine the optimal contact state and guide the operator to achieve proper probe positioning without applying excessive force that would deform the skin
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
Enhances the accuracy of registering magnetic tracking systems with subject images by ensuring precise contact and positioning, reducing errors associated with probe placement and improving the reliability of medical procedures.
Implementation Method 1
A contact sensor, located within the distal end and configured to output first signals indicative of a quality of the contact between the distal end with the one or more registration points
Implementation Method 2
a magnetic detector, located within the distal end and configured to output second signals in response to the magnetic field that are indicative of respective positions of the one or more respective registration points in a coordinate frame of the magnetic tracking system
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Apparatus, including a magnetic tracking system, which generates a magnetic field near a living subject's body, and a probe, having a distal end that can contact registration points on a surface of the body. The probe has a contact sensor, located within the distal end, that outputs first signals indicative of a quality of the contact between the distal end with the registration points. Located within the distal end is a magnetic detector that outputs second signals that are indicative of respective positions of the registration points in a coordinate frame of the magnetic tracking system. A processor receives a tomographic image of the subject, and verifies, based on the quality of the contact indicated by the first signals, that the registration points are valid, and registers the tomographic image in the coordinate frame of the magnetic tracking system using the positions of the valid registration points.