Virtual Camera Placement in Sinus Cavities Using 3D Image Segmentation
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Solution Overview
Problem
Accurately positioning a virtual camera within a body cavity, such as a sinus opening, is challenging due to the small and narrow nature of these openings, and the need for a 3D camera placement from 2D CT image slices, which complicates precise alignment during medical procedures.
Innovation Solution
A method using 3D image data to identify a seed location for the virtual camera by filling the body cavity with points, applying a growing spheres algorithm to find the local minimum distance to the cavity wall, and selecting the point with the minimal grown diameter as the entrance, facilitating accurate camera placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ray casting is used to find the longest ray from camera position to wall for orienting virtual camera, then the virtual camera can be positioned in the lumen, but the method fails to accurately locate narrow openings and small cavities
Solution Approach 1:
The patent segments the cavity detection problem into multiple steps: filling the cavity with candidate points, evaluating each point's accessibility, and selecting the optimal opening location based on multiple criteria including ray length and solid angle. This segmentation allows the system to handle both narrow openings and larger cavities effectively.
Solution Approach 2:
The patent introduces a new evaluation dimension by calculating the solid angle subtended by the opening at each candidate point, in addition to ray length. This dimensional addition enables more accurate identification of openings in narrow cavities where traditional single-criteria methods fail.
2Manufacturing precision
If traditional ray casting methods are used for camera orientation, then the process is simple, but the precision of camera placement in 3D space from 2D slices is compromised
Solution Approach 1:
The patent performs preliminary actions by first filling the entire cavity volume with candidate points before selecting the optimal opening location. This pre-positioning of multiple candidate points allows for systematic evaluation and ensures accurate 3D camera placement without requiring complex real-time adjustments during the procedure.
Solution Approach 2:
The patent introduces an intermediary evaluation process that assesses each candidate point based on multiple criteria (ray length, solid angle, accessibility) before final camera placement. This intermediary step acts as a mediator between the 2D image data and 3D camera positioning, ensuring precision while managing algorithmic complexity.
3Measurement precision
If the cavity is filled with multiple points and evaluated for minimum distance to wall, then the opening location accuracy improves, but the computational time increases
Solution Approach 1:
The patent applies partial action by evaluating only the necessary properties of each candidate point (minimum distance to wall, solid angle, ray length) rather than performing exhaustive analysis. This selective evaluation maintains high accuracy in opening identification while reducing unnecessary computational overhead and processing time.
Data Source
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AI summary
Methods, apparatus and computer program products implement embodiments of the present invention that include receiving three-dimensional (3D) image data with respect to a 3D region including body tissue in a living body, and segmenting the 3D image data so as to identify a cavity within the body tissue and a wall surrounding the cavity. For each point among a plurality of points in the cavity, a respective minimum distance from the point to the wall is found, and among the plurality of the points, a set of one or more points for which the respective minimum distance is a local maximum relative to neighboring points in the plurality is found. One of the points in the set for which the respective minimum distance is minimal among the one or more points in the set is then identified as an entrance to the cavity.