Hybrid Electromagnetic and X-ray Medical Instrument Localization
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Solution Overview
Problem
Current X-ray-free methods for locating medical instruments during interventions suffer from limited accuracy due to electromagnetic or electric field distortions, leading to exposure risks and inaccuracies, while fluoroscopic methods provide high accuracy but at the cost of high radiation exposure.
Innovation Solution
A method that combines X-ray image recording and electromagnetic locating systems, where continuous positional information from the locating system is intermittently corrected using X-ray images, reducing radiation exposure and enhancing accuracy by accounting for electromagnetic field distortions through a distortion field adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluoroscopy-based X-ray methods are used to locate the medical instrument, then positioning accuracy is improved (submillimeter range), but radiation exposure to patient and medical personnel increases significantly
Solution Approach 1:
The patent combines electromagnetic field-based localization (for continuous, radiation-free tracking) with intermittent fluoroscopy verification (for high-accuracy reference measurements) into a hybrid system. The fluoroscopy images serve as ground truth to correct drift in the electromagnetic localization system, achieving both reduced radiation exposure and maintained accuracy.
Solution Approach 2:
Instead of continuous fluoroscopy, the system uses periodic or intermittent X-ray imaging at selected time points to update and correct the electromagnetic localization data. This periodic verification approach maintains positioning accuracy while minimizing cumulative radiation exposure to acceptable levels.
2Object-affected harmful factors
If electromagnetic coil-based locating systems are used to reduce radiation exposure, then radiation exposure is reduced, but positioning accuracy deteriorates (0.5 to 5 mm accuracy)
Solution Approach 1:
The system uses fluoroscopy-based position measurements as feedback to continuously correct and calibrate the electromagnetic localization system. By comparing electromagnetic-derived positions with fluoroscopy-verified positions and applying corrections, the system maintains high accuracy while operating primarily in the low-radiation electromagnetic mode.
Solution Approach 2:
The system dynamically adjusts the operational parameters of the electromagnetic localization, using fluoroscopy verification to compensate for field distortions caused by changing surgical conditions, patient movements, or introduction of metallic instruments. This allows the electromagnetic system to maintain accuracy despite varying environmental parameters.
3Object-affected harmful factors
If impedance-measuring systems are used for locating, then radiation exposure is reduced, but positioning accuracy deteriorates significantly (errors in centimeter range)
Solution Approach 1:
The patent introduces fluoroscopy-based position measurement as an intermediary reference system that mediates between the low-accuracy impedance measurements and the ground truth anatomical positions. This intermediary verification layer corrects the large errors inherent in impedance-based localization, enabling accurate tracking without radiation-intensive continuous fluoroscopy.
4Measurement precision
If complex calibrating techniques are applied to compensate for field distortions in electromagnetic locating systems, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The system performs self-calibration and self-correction by using its own fluoroscopy verification capability to detect and compensate for electromagnetic field distortions. Rather than requiring external complex calibration procedures, the system autonomously adjusts for distortions caused by patient anatomy, surgical tools, or environmental factors through periodic fluoroscopy reference measurements.
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 significantly reduces radiation exposure for patients and medical personnel while achieving high positional accuracy, allowing for more precise medical instrument tracking with reduced frequency of X-ray image recordings and improved accuracy in demanding applications.
Implementation Method 1
at least three stationary coils via which an electromagnetic signal is sent. The received signal from which the medical instrument's position can be determined through determining the distances from the transmitter coils and triangulation is measured.
Implementation Method 2
recording two X-ray images of the region at the intervention site that are recorded at different angles and both show the medical instrument, and for determining and, where applicable, displaying the three-dimensional position of the medical instrument through back projection.
Implementation Method 3
the first item of positional information will be corrected depending on the comparison result taking account of the second item of positional information obtained from the X-ray images
Data Source
AI summary
The invention relates to a method for locating a medical instrument during an intervention performed on the human body using an X-ray image recording system and an electromagnetic locating system whose systems of coordinates have been or will be mutually registered, with a first item of positional information about the instrument being obtained continuously by means of the locating system and in each case two two-dimensional X-ray images positioned at an angle to each other being intermittently recorded by means of the X-ray image recording system, from which images a second item of positional information about the instrument is determined and compared with the first item of positional information, after which the first item of positional information will be corrected depending on the comparison result taking account of the second item of positional information obtained from the X-ray images.