Fluoroscope-Mounted Registration Fixture for Surgical Navigation
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Solution Overview
Problem
The process of co-registering two-dimensional medical images with a three-dimensional tracking space is challenging, especially due to imaging artifacts in older fluoroscopy machines, and differs from the co-registration of three-dimensional medical image volumes like CT scans, requiring improved systems and methods for accurate registration.
Innovation Solution
The use of a registration fixture with rings as an alternative to spherical fiducials, mounted to a fluoroscope instead of the patient, and incorporating distortion correction, allows for the construction of a three-dimensional image volume from two-dimensional images and their co-registration with the tracking space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If spherical fiducials are used for registration, then the registration process is well-defined, but the system cannot be mounted to the fluoroscope and is limited to patient-based registration
Solution Approach 1:
The patent inverts the traditional registration approach by mounting the registration fixture to the fluoroscope rather than to the patient. This allows the fiducials to move with the fluoroscope, enabling dynamic registration that adapts to different fluoroscopic positions and angles during the procedure.
Solution Approach 2:
The registration fixture serves as an intermediary between the fluoroscope and the navigation system. It provides a stable reference frame that mediates the relationship between the moving fluoroscope and the static navigation coordinate system, enabling accurate co-registration.
2Manufacturing precision
If fluoroscopic images are taken at exact 90 degrees, then the geometric relationship is simplified, but the system lacks flexibility in image acquisition angles
Solution Approach 1:
The system transitions from a static geometric assumption (fixed 90-degree angles) to a dynamic solution where the registration fixture moves with the fluoroscope. This allows the system to maintain geometric accuracy while adapting to various imaging angles and positions during the procedure.
Solution Approach 2:
The patent changes the reference frame parameters by attaching fiducials to the fluoroscope itself. This allows the system to accommodate variable imaging angles by dynamically updating the coordinate transformation parameters rather than relying on fixed geometric assumptions.
3Productivity
If distortion correction is not applied, then the processing is simpler, but the registration accuracy deteriorates due to fluoroscopy artifacts
Solution Approach 1:
The system applies distortion correction as a preliminary step in the image processing pipeline, before registration and navigation. This pre-processing approach corrects fluoroscopy artifacts and geometric distortions early, ensuring that subsequent registration operations work with corrected images and achieve higher accuracy without significantly impacting overall processing time.
Data Source
AI summary
A registration fixture for use with a surgical navigation system for registration of a medical image or images to a three-dimensional tracking space that includes a first ring having at least one tracking marker, a second ring coupled to the first ring having at least one tracking marker and wherein the first ring and the second ring are spaced apart from one another and further include optical markers.