Online Stereo Calibration for Surgical 3D Accuracy
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Solution Overview
Problem
Existing surgical imaging systems face challenges with calibration drift and repositioning errors during minimally invasive surgeries, leading to inaccuracies in 3D reconstructions and tool tracking.
Innovation Solution
Implementing a system for online stereo calibration that monitors and updates calibration during procedures using tool geometry or patient anatomy characteristics to maintain accuracy, allowing for real-time recalibration when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used during surgical procedures, then initial calibration accuracy is achieved, but calibration drift and repositioning errors occur over time leading to 3D reconstruction inaccuracies
Solution Approach 1:
The system performs continuous online calibration throughout the surgical procedure rather than relying on a single pre-procedure calibration. The calibration process is made continuous by repeatedly capturing images of calibration targets, computing calibration parameters, and updating the stereo camera system's calibration state throughout the procedure, thereby eliminating calibration drift and maintaining measurement precision over time.
Solution Approach 2:
The system implements feedback by continuously monitoring the calibration state through repeated image capture and analysis of calibration targets. The computed calibration parameters are fed back to update the system's calibration model, allowing the system to detect and correct calibration drift in real-time, thereby maintaining both accuracy and reliability throughout the surgical procedure.
2Measurement precision
If online stereo calibration is implemented to correct calibration drift, then 3D reconstruction accuracy is maintained, but system complexity and processing requirements increase
Solution Approach 1:
The system performs preliminary calibration by capturing images of calibration targets at the beginning of the procedure to establish initial calibration parameters. This preliminary action provides a baseline calibration state that can be referenced and corrected against during continuous online calibration, simplifying the overall calibration process while maintaining accuracy.
Solution Approach 2:
The system uses calibration targets with known geometric patterns that create simplified, repeatable image copies across the stereo camera pair. These standardized calibration target images provide consistent reference data that simplifies the computation of calibration parameters and reduces processing complexity compared to calibrating arbitrary surgical scenes.
3Measurement precision
If frequent recalibration is performed to maintain precision, then calibration drift is corrected, but surgical procedure time is extended
Solution Approach 1:
The system performs calibration updates at periodic intervals during the surgical procedure by capturing calibration target images at scheduled moments. This periodic calibration approach balances the need for maintaining accuracy with the constraint of procedure time, updating calibration parameters frequently enough to correct drift but not so frequently as to significantly extend the surgical procedure.
Solution Approach 2:
The system rapidly captures calibration target images and computes calibration parameters in streamlined sequences, minimizing the time spent on calibration activities. By optimizing the calibration workflow to execute quickly and efficiently, the system maintains measurement precision while reducing the time loss associated with frequent recalibration during the surgical procedure.
Data Source
AI summary
A stereo calibration system for minimally invasive surgery including a first image sensor configured to capture one or more first images of a patient anatomy and a second image sensor configured to capture one or more second images of a patient anatomy. The system further includes a processor configured to obtain calibration data associated with the first image sensor and the second image sensor, identify, based on a comparison of the one or more first images against the one or more second images, an offset, determine, based on the offset and the calibration data, whether the first image sensor or the second image sensor require re-calibration; and perform, based on the determination, at least one action.