Surgical site measurement, and camera calibration using fiducial markers on surgical tools
Inventors
Assignees
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Publication Number
US-12220226-B2
Publication Date
2025-02-11
Expiration Date
Abstract
Calibration of parameters of an endoscopic or laparoscopic camera is conducted while the camera is in use capturing images of a surgical procedure at a surgical site. The surgical procedure is performed using a surgical instrument marked with a fiducial pattern. A processor receives image data from images captured by the camera and uses machine vision to detect points of the pattern, and carries out an optimization to determine the 3D pose of the surgical instrument relative to the camera and the camera parameters. Once calibration parameters are determined, 3D measurements between measurement points in the body cavity may be estimated.
Core Innovation
The invention provides a system and method for measuring distances within a surgical site in a body cavity using a camera positionable to capture image data corresponding to a surgical site. A surgical instrument is positioned within the body cavity and includes an elongate shaft with a fiducial calibration pattern thereon, so that the fiducial calibration pattern and the camera are disposed together within the body cavity during image capture. The system analyzes a plurality of frames of images of the fiducial calibration pattern captured by the camera and determines locations of fiducials in the calibration pattern across the frames.
Based on the known geometry of the fiducials and the locations determined across the plurality of frames, the system estimates intrinsic camera parameters for the camera. The invention further determines relative 3D positions of identified measurement points in the treatment site captured in images captured by the camera, estimates a distance between the identified measurement points, and generates output communicating the estimated distance to a user.
The invention is configured to perform calibration during a live surgical procedure while imaging surgical instruments marked with fiducial patterns, rather than occupying OR time/space with a pre-surgery calibration stage. The approach supports estimating intrinsic camera parameters while the fiducial calibration pattern is disposed within the body cavity, and can account for different camera configurations such as mono and stereo and different scope configurations.
Claims Coverage
The document provides two independent claims. Each independent claim centers on imaging a surgical instrument bearing a fiducial calibration pattern to estimate intrinsic camera parameters and then estimating a three-dimensional distance between identified measurement points within a body cavity; the first claim emphasizes system components and user output, while the second claim emphasizes the method workflow starting with positioning the camera and instrument in the body cavity.
Fiducial-patterned surgical instrument for camera intrinsic parameter estimation in-body
The system uses at least one surgical instrument positionable in a body cavity, the surgical instrument including an elongate shaft and a fiducial calibration pattern on the elongate shaft, and analyzes a plurality of frames of images of the fiducial calibration pattern captured by the camera with both the camera and the fiducial calibration pattern of the elongate shaft disposed within the body cavity to determine locations of fiducials in the calibration pattern in the plurality of frames.
Estimating intrinsic camera parameters from known fiducial geometry
Based on known geometry of the fiducials, the system estimates intrinsic camera parameters for the camera from the determined fiducial locations in the plurality of frames.
Relative 3D measurement point localization and distance estimation
The system determines relative 3D positions of identified measurement points in the treatment site captured in images captured by the camera, estimates a distance between the identified measurement points, and generates output communicating the estimated distance to a user.
In-body positioning of camera and fiducial-patterned instrument for intrinsic parameter estimation
The method positions a camera with its distal end at a surgical treatment site within a body cavity, provides a surgical instrument having a fiducial calibration pattern thereon, and positions the surgical instrument such that the fiducial calibration pattern is disposed within the body cavity; with the distal end of the camera within the body cavity, the method uses the camera to capture a plurality of images of the surgical instrument.
Estimating camera intrinsic parameters and 3D distance in the surgical site
The method determines locations of scene points in the fiducial calibration pattern in a plurality of frames of the images and, using the locations of the scene points and a known geometry of the fiducial calibration pattern, estimates intrinsic parameters of the camera, and then estimates, from captured images of the surgical site, a three-dimensional distance between identified measurement points within the surgical site.
Across the independent claims, the core inventive coverage is the concurrent in-body capture of fiducial calibration pattern images on an instrument to estimate intrinsic camera parameters, followed by estimating a three-dimensional distance between identified measurement points in the surgical site and (in the system claim) outputting the estimated distance to a user.
Stated Advantages
On-the-fly calibration without pre-surgery calibration patterns occupying OR time/space.
Support for mono/stereo and varying scope configurations.
Documented Applications
Measuring distances within a surgical site in a body cavity for use during a live surgical procedure.
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