Coordinate Transformation Verification for X-ray Navigation Systems
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Solution Overview
Problem
Conventional surgical navigation systems face challenges in accurately determining and verifying the coordinate transformation between X-ray systems and surgical operation navigation systems, particularly during intraoperative procedures, leading to potential inaccuracies in positioning surgical instruments within tomographic images.
Innovation Solution
A method and apparatus for determining and verifying the coordinate transformation using a reference object with marking elements, detected by both the surgical operation navigation system and the X-ray system, allowing for automatic quality control and adaptation of image recording to ensure accurate navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a marking ring is arranged on the image intensifier and a reference star on the patient for coordinate transformation determination, then the coordinate transformation between X-ray system and navigation system can be established, but the accuracy verification is insufficient and deviations may exceed acceptable thresholds
Solution Approach 1:
The patent implements a feedback mechanism by detecting the actual position of the reference star with both the navigation system and X-ray system, comparing the detected positions, calculating deviation, and automatically adjusting the coordinate transformation parameters. This closed-loop feedback ensures the transformation accuracy remains within predetermined thresholds, resolving the contradiction between measurement precision and system reliability.
Solution Approach 2:
The patent performs preliminary calibration by arranging marking elements on the reference star and capturing their positions with both systems before the actual surgical navigation. This preliminary action establishes the initial coordinate transformation relationship and enables subsequent accuracy verification and adjustment, ensuring reliable navigation from the outset.
2Measurement precision
If manual verification of coordinate transformation is performed by visually checking pointer instrument contact points, then the transformation accuracy can be assessed, but the process is time-consuming and subject to human error
Solution Approach 1:
The patent replaces the manual visual verification process with an automated computational system. The computer automatically detects marking element positions, calculates coordinate transformations, determines deviations, and performs adjustments without human intervention. This substitution of mechanical/manual operations with automated computational processes eliminates human error and significantly reduces verification time while maintaining high measurement precision.
Solution Approach 2:
The system performs self-verification and self-correction of the coordinate transformation. The computer automatically compares positions detected by both systems, calculates deviations, and adjusts transformation parameters without requiring external manual verification. This self-service capability eliminates time-consuming manual processes while ensuring accurate transformation.
3Loss of information
If the C-arm is pivoted into multiple positions for three-dimensional image reconstruction, then comprehensive interior image data is obtained, but the coordinate transformation determination becomes more complex
Solution Approach 1:
The patent uses a universal reference star with marking elements that serves multiple functions: it is detectable by both the navigation system's stereoscopic camera and the X-ray system, and it remains effective across multiple C-arm pivoting positions. This universal reference object simplifies the coordinate transformation determination despite the complexity of multi-position imaging, as the same reference features are used throughout the process.
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 enhances the accuracy of surgical navigation by enabling automatic verification of coordinate transformations, reducing deviations to within a predetermined threshold, thereby improving the precision of surgical instrument positioning during operations.
Implementation Method 1
The marking elements are made of a material, or provided with a coating, which reflects infrared radiation
Implementation Method 2
The image data obtained thereby represents the attenuation of an X-ray beam on passing through tissue with the respective projection
Data Source
AI summary
The device enables the detection of positions of the navigation marking elements on a reference star by way of at least two projection images taken by an X-ray system at different pivoting angles of a C-arm. The positions of the navigation marking elements on the reference star are also calculated by a navigation system tracking camera. The transformation from the coordinate system of the navigation system into the coordinate system of the X-ray system is calculated from the position of the reference star detected by the X-ray system and the position of the reference star detected by the tracking camera. The navigation marking elements are located outside of the volume which is reconstructed by way of the imaging process in order to prepare tomographic images. The positions of the navigation marking elements are determined from two-dimensional projections. All the navigation marking elements need only be detected by at least two projection images.