Estimating Roll Angle of Asymmetric Medical Instrument Heads

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Solution Overview

Problem

Existing medical instruments lack accurate tracking of the rotational orientation of distal ends within organs, which hinders precise operation during invasive procedures.

Innovation Solution

A system comprising a medical instrument with a rotationally-asymmetric head, a position sensor that responds to an externally-applied magnetic field, and a processor that estimates the roll angle of the head based on the sensor signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a position sensor is used to track the location of the medical instrument, then the position tracking is improved, but the rotational orientation tracking is insufficient

Engineering Contradiction:

Improveposition trackingVSAvoidrotational orientation information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent transitions from tracking only positional information (3D coordinates) to including rotational orientation information (roll angle), effectively adding another dimension of measurement. The position sensor is enhanced to detect not just location but also the rotational state of the instrument's head relative to the longitudinal axis.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent utilizes the rotationally-asymmetric feature of the head in combination with the position sensor to encode rotational information. By detecting how the asymmetric feature orientates within the magnetic field, the system can determine the roll angle, converting a structural asymmetry into a useful measurement dimension.

Inventive Principle:

Principle #4Asymmetry

2Measurement precision

If the head is made rotationally-asymmetric to enable roll angle tracking, then the measurement capability is improved, but the device complexity increases

Engineering Contradiction:

Improveroll angle measurementVSAvoidinstrument structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The rotationally-asymmetric feature of the head serves dual purposes: it performs its primary medical function while simultaneously providing the geometric signature needed for roll angle detection. The existing asymmetric geometry is repurposed to encode rotational information, eliminating the need for additional dedicated tracking components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The position sensor on the head performs multiple functions: it tracks the 3D position of the instrument tip and simultaneously detects the roll angle through its interaction with the rotationally-asymmetric feature. This multi-functionality reduces the need for separate sensing systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If magnetic field radiators are added to enable rotational tracking, then the tracking accuracy is improved, but the system complexity and cost increase

Engineering Contradiction:

Improverotational orientation tracking accuracyVSAvoidsystem components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the rotationally-asymmetric feature as an intermediary between the position sensor and the magnetic field. This asymmetric geometry acts as a passive marker that modulates the magnetic field signals in a way that encodes rotational information, eliminating the need for active rotational sensors or additional magnetic field radiators.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex mechanical rotational sensors with a magnetic field-based detection approach. By using the position sensor's ability to detect magnetic field variations caused by the asymmetric feature's orientation, the system substitutes mechanical measurement with electromagnetic sensing.

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

Enables accurate tracking and rendering of the rotational orientation of medical instruments within organs, enhancing the precision and safety of invasive procedures.

Implementation Method 1

a position sensor disposed on the head and configured to generate signals in response to an externally-applied magnetic field

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the position sensor includes at least a coil having an axis oriented at a given rotational angle relative to the rotationally-asymmetric feature of the head

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12336767B2Finding roll angle of distal end of deflectable or non-deflectable invasive medical instrument

Publication Date: 2025.06.24 BIOSENSE WEBSTER (ISRAEL) LTD

AI summary

A system includes a medical instrument, a position sensor, and a processor. The medical instrument includes a handle and a head, the head being configured for insertion into an organ of a patient and having a feature that is rotationally-asymmetric about a longitudinal axis of the medical instrument. The position sensor, which is disposed on the head and is configured to generate signals in response to an externally-applied magnetic field. The processor is configured to receive the signals generated by the position sensor on the head, and estimate, based on the received signals, a roll angle of the rotationally-asymmetric feature of the head.