3D Localization from 2D X-ray via Template Matching
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Solution Overview
Problem
Current methods for three-dimensional localization of interventional medical devices using x-ray fluoroscopy lack depth information, are costly, and expose patients to excessive radiation, with existing solutions requiring specialized markers or expensive non-x-ray based systems.
Innovation Solution
A method for determining the three-dimensional location of an object from a two-dimensional x-ray image using template images and iterative similarity measures, reducing radiation exposure and costs by leveraging standard x-ray fluoroscopy systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bi-plane imaging system is used for three-dimensional localization, then depth information is obtained, but x-ray radiation exposure to patient increases
Solution Approach 1:
The patent creates a virtual three-dimensional model (copy) of the medical device based on two-dimensional x-ray images. Instead of using a physical bi-plane imaging system that exposes the patient to radiation, the invention synthesizes a three-dimensional representation by processing standard single-view fluoroscopy images through template matching and iterative optimization algorithms, thereby obtaining depth information without additional radiation exposure.
Solution Approach 2:
The patent replaces the mechanical bi-plane imaging system with a computational image processing system. Rather than physically acquiring images from two perspectives using additional hardware, the invention uses software-based template matching, similarity measures, and optimization algorithms to extract three-dimensional position information from standard two-dimensional fluoroscopy images.
2Measurement precision
If specialized non-x-ray based catheter tracking systems are used, then accurate three-dimensional localization is achieved, but capital and per-use cost increases significantly
Solution Approach 1:
The patent makes the standard x-ray fluoroscopy system multi-functional by enabling it to perform both its traditional two-dimensional imaging function and three-dimensional localization function. The same hardware infrastructure is used for both purposes through software processing, eliminating the need for separate expensive tracking systems like CARTO or EnSite.
Solution Approach 2:
The invention creates a virtual three-dimensional model of the medical device using computational methods. By synthesizing a three-dimensional representation from standard two-dimensional fluoroscopy images through template matching and optimization, the system achieves accurate localization without requiring specialized expensive hardware tracking systems.
3Measurement precision
If specialized markers are affixed to interventional devices for three-dimensional localization, then position and orientation can be determined, but device modification is required which may affect performance and safety
Solution Approach 1:
The patent extracts three-dimensional position and orientation information directly from the existing visual features of the medical device as seen in standard fluoroscopy images. Instead of adding specialized markers to the device, the method identifies and tracks the device's inherent radiopaque features and geometric characteristics, thereby determining its spatial parameters without any device modification.
Solution Approach 2:
The medical device serves its own localization function through its inherent radiopaque features visible in standard fluoroscopy. The device's own structural characteristics (such as catheter shape, radiopaque markers already present on the device, or geometric features) are used as the basis for three-dimensional localization, eliminating the need for additional specialized markers or modifications.
4Measurement precision
If template matching with iterative optimization is used, then three-dimensional localization is achieved with standard x-ray systems, but computational processing time increases
Solution Approach 1:
The patent performs preliminary actions by pre-defining template images of the medical device at various orientations and positions before actual localization occurs. These pre-computed templates are stored and ready for rapid comparison with incoming fluoroscopy images, reducing the computational burden during real-time processing.
Solution Approach 2:
The optimization process focuses on refining only the critical parameters (position and orientation) rather than searching the entire parameter space. The iterative optimization starts with an initial estimate and makes localized adjustments, performing partial optimization on the most important degrees of freedom to achieve sufficient accuracy without exhaustive computation.
Data Source
AI summary
A method for determining the three-dimensional location of an object in real-time from a two-dimensional medical image obtained with a medical imaging system is provided. For example, the three-dimensional location of an interventional medical device or a marker positioned on such a device may be determined from a two-dimensional x-ray image obtained with an interventional x-ray imaging system. Template images corresponding to the object under different imaging geometries and orientations are produced and are compared to images acquired with the medical imaging system. Similarity measures, such as normalized cross correlation and normalized similarity integral, are used to determine the similarity between a selected template image and the medical images in different stages of refining the position information for the object.