Moiré Marker X-Ray Imaging Rotational Tracking
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Solution Overview
Problem
Current x-ray imaging technologies require external tracking systems or multiple image recordings, leading to potential collision dangers, increased x-ray doses, and obstructed surgical fields due to the need for large marker structures to achieve accurate alignment and tracking of robotic instruments and non-rigid body parts.
Innovation Solution
The use of a Moiré marker that generates a Moiré pattern in x-ray images, allowing for the determination of rotational position within a single image without external tracking systems, reducing the need for image source and detector movement, and enabling compact marker structures for precise alignment and tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external tracking systems are used for tracking movements of robotic instruments, then tracking accuracy is improved, but device complexity and surgical field obstruction increase
Solution Approach 1:
The patent extracts the tracking function from external tracking systems and integrates it directly into the x-ray imaging device. The x-ray imaging device itself is used to capture images and determine positional information, eliminating the need for separate external tracking systems while maintaining tracking accuracy.
Solution Approach 2:
The x-ray imaging device is designed to perform multiple functions: both imaging and tracking. By using the same device for both purposes, the patent reduces overall system complexity while maintaining the accuracy benefits of dedicated tracking systems.
2Measurement precision
If multiple images are recorded to determine positional information, then measurement accuracy is improved, but x-ray dose and imaging time increase
Solution Approach 1:
The patent uses a pre-defined relationship between the marker structure and the object to be tracked. This allows the system to determine positional information from a single image without requiring multiple images or complex movements, thereby reducing x-ray exposure while maintaining accuracy.
Solution Approach 2:
The patent changes the approach from capturing multiple images with different geometries to capturing a single image and using computational methods with pre-defined relationships to extract positional information. This reduces the number of x-ray exposures while maintaining measurement accuracy.
3Measurement precision
If large marker structures are used to achieve good accuracy in all dimensions, then measurement precision is improved, but surgical field obstruction increases
Solution Approach 1:
The patent uses a planar marker structure with a specific geometric pattern that encodes three-dimensional positional information in a two-dimensional image. The marker consists of a plane with a defined relationship to the object, allowing accurate 3D tracking from 2D x-ray images without requiring large physical structures.
Solution Approach 2:
The patent changes from using large spherical markers to a planar marker structure with encoded geometric patterns. This allows the same or better measurement precision to be achieved with a much smaller physical footprint, reducing obstruction of the surgical field.
4Measurement precision
If image source and detector are moved significantly for registration, then measurement accuracy is improved, but collision danger and imaging time increase
Solution Approach 1:
The patent pre-defines the geometric relationship between the marker structure and the object to be tracked. This allows accurate coordinate system registration to be achieved without significant movement of the image source and detector, thereby reducing collision danger while maintaining registration 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 enhances operational safety by eliminating external tracking systems, reducing x-ray doses, and improving alignment accuracy with a single image, while allowing for high angle resolution and efficient tracking of non-rigid body parts.
Implementation Method 1
The Moiré marker for x-ray imaging generates a Moiré pattern of x-ray signal intensities on an x-ray image. The Moiré pattern is indicative for an angle between the Moiré marker and an x-ray propagation direction of the x-ray imaging device.
Data Source
AI summary
The present invention relates to a computer-implemented method of determining a rotational position of an object in a coordinate system of an x-ray imaging device. An x-ray image is generated of an object to which a Moiré marker for x-ray imaging is attached. Subsequently, the Moiré pattern generated by the Moiré marker is analysed and the rotational position of the marker and hence of the object is determined in a calculative manner. The Moiré marker for x-ray imaging includes a pattern which results in a significantly different appearance when being observed from slightly different perspectives. One embodiment example of the Moiré marker for x-ray imaging consists of two layers with patterns produced by a material that shields x-ray as good as possible like for example lead, surrounded and spaced apart by material that is highly transparent in x-ray like for example air or light plastics. The size of the openings in the pattern shall preferably be small compared to the distance of the two layers such that a small change in orientation of the marker results in a fairly significant change in the structure of the second layer seen through the aperture of the first layer. Multiple structures with different hole sizes and layer distances can be used to have a larger working range while maintaining accuracy.