Interventional Instrument Positioning via Calibration Object Registration
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Solution Overview
Problem
Existing interventional systems face challenges in accurately registering projection devices with tracking devices for determining the location of interventional instruments in projection images, leading to inaccuracies in displaying the tracked location of instruments within the body during procedures.
Innovation Solution
A positions determination apparatus that uses a combination of projection images and three-dimensional representations of interventional instruments, allowing users to indicate the instrument tip's position, and employs spatial transformations and curvature analysis to accurately determine the instrument's location, thereby improving registration between projection and tracking devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If registration is performed by detecting the location of the interventional instrument in several projection images and determining registration parameters, then the registration between projection device and tracking device can be established, but the accuracy of registration is insufficient
Solution Approach 1:
The patent introduces a calibration object with known geometric structure as an intermediary between the projection device and tracking device. The calibration object serves as a common reference that both devices can measure, enabling accurate registration without directly relying on the interventional instrument's position detection. The known geometry of the calibration object provides a reliable basis for calculating transformation parameters between coordinate systems.
Solution Approach 2:
The patent creates a virtual model (copy) of the calibration object with precise known dimensions and geometry. This virtual copy is used to generate expected projection images and track positions, which are then compared with actual measurements. The comparison and optimization process refines the registration parameters, improving accuracy without requiring direct physical measurement of the interventional instrument.
2Measurement precision
If the tracking device and projection device are registered based on tracked location and detected locations, then the display can show tracked location overlaid with projection image, but the registration accuracy is not sufficient for precise interventional procedures
Solution Approach 1:
The patent performs preliminary calibration by measuring the calibration object's positions with both the projection device and tracking device before actual interventional procedures. This preliminary action establishes the registration parameters and transformation relationships in advance, so that during the procedure, accurate position determination can be achieved without complex real-time calculations or additional complexity.
3Ease of operation
If simple location detection methods are used for registration, then the system operation is simpler, but the measurement precision of instrument positions is insufficient
Solution Approach 1:
The calibration object is designed with self-identifying geometric features and known dimensions that enable automatic recognition and measurement by both devices. The object's inherent structure provides its own reference information, eliminating the need for complex manual measurement procedures or additional marking steps, thus maintaining operational simplicity while achieving high precision.
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 enables precise determination of interventional instrument positions in projection images, enhancing the accuracy of registration between projection and tracking devices, which improves the display and tracking of instruments during procedures.
Implementation Method 1
The projection device comprises a radiation source for emitting radiation for traversing the person and a detector with a detection surface for detecting the radiation after having traversed the person
Data Source
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AI summary
The invention relates to a positions determination apparatus for determining positions, at which an interventional instrument (3) is located, in a projection image. An input unit (16) allows a user to indicate the position of a tip (23) of the interventional instrument (3) in the projection image, wherein the positions, at which the interventional instrument is located, in the projection image are determined based on the projection image, the indicated tip position and a three-dimensional representation of the interventional instrument, which is defined by its position and shape as determined by a tracking device like an OSS device. By using the projection image, the indicated tip position and the representation the positions in the projection image, at which the interventional instrument is located, can be determined very accurately. Based on these determined positions the projection device and the tracking device can be very accurately registered to each other.