X-ray C-arm Non-circular Path for 3D Reconstruction
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Solution Overview
Problem
Conventional 3D reconstruction methods using x-ray C-arms struggle to effectively map regions of interest outside the center point of an object, leading to potential collisions and incomplete reconstruction, particularly when trying to image areas like the liver.
Innovation Solution
The method involves calculating and tracking the x-ray C-arm to move in a non-circular path, ensuring the flat panel detector remains tangential to an envelope surrounding the patient, allowing the region of interest to be within the x-ray beam cone at each rotation angle, using a 6-axis articulated arm robot to maintain collision-free movement and adjust for high resolution or large volume representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the x-ray C-arm is moved along a circular path through 180° to record images from different directions, then 3D reconstruction can be performed, but the region of interest beyond the center point cannot be completely mapped and collisions occur
Solution Approach 1:
The patent transitions from a static circular movement path to a dynamic tracking path. The C-arm's movement is continuously adjusted based on real-time positioning relative to the region of interest, allowing the system to adapt its trajectory to map regions beyond the center point while maintaining safe distances from the patient's body.
Solution Approach 2:
The patent introduces an envelope model as an intermediary representation of the patient's body boundaries. This mathematical envelope serves as a mediator between the C-arm's movement control and the actual patient geometry, enabling collision-free path planning by ensuring the C-arm trajectory remains outside the envelope while still achieving complete mapping of the region of interest.
2Adaptability or versatility
If the region of interest is located beyond the center point of the object, then new center point definition is needed, but the x-ray source or detector would knock against the patient
Solution Approach 1:
The system dynamically determines the optimal center point for each region of interest rather than using a fixed anatomical center. The C-arm's movement path is continuously recalculated based on the region's location, allowing adaptation to regions beyond the original center point while maintaining collision-free operation through real-time trajectory adjustment.
Solution Approach 2:
The patent changes the parameters of the movement path by introducing non-circular trajectories. Instead of maintaining a fixed circular path centered on the patient, the system varies the path parameters (radius, center position, angular velocity) to optimize mapping of the region of interest while keeping the C-arm at safe distances from the patient's body boundaries defined by the envelope.
3Object-affected harmful factors
If the flat panel detector is positioned to touch the envelope tangentially, then collision-free movement is achieved, but the region of interest must be precisely positioned within the x-ray beam cone
Solution Approach 1:
The system employs feedback mechanisms to continuously monitor the C-arm's position relative to the envelope and the region of interest. Based on this feedback, the movement trajectory is dynamically adjusted to maintain tangential contact with the envelope while ensuring the region of interest remains within the x-ray beam cone, balancing collision prevention with mapping accuracy.
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 enables optimal 3D reconstruction by preventing collisions and ensuring complete mapping of the region of interest, allowing for high-resolution or large-volume representation of the region of interest in x-ray images, effectively overcoming the limitations of conventional circular path movements.
Implementation Method 1
an x-ray C-arm which supports an x-ray source and a flat panel detector
Data Source
AI summary
When recording an image sequence, it is possible to deviate from passing through a perfect curve path. There is described how an alternative curve path can be determined. An envelope is determined, a point is determined, which is the center point of the region of interest and then the detector is moved such that it is at right angles in each instance to a line which emanates from the point and simultaneously touches the envelope tangentially. As a result, the region of interest is mapped as optimally as possible in the image sequence so that as good a 3D reconstruction as possible can be obtained.