C-arm CT Patient Couch Positioning via Image Coordinate Transformation
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Solution Overview
Problem
Current methods for positioning a patient couch in C-arm computed tomography systems are time-consuming and require manual adjustment by operators to align the isocenter with specific body organs, often necessitating multiple x-ray images for accurate positioning.
Innovation Solution
A method that involves receiving pre-captured image data from a different system, allowing selection of specific pixels or areas within the image data, calculating the required coordinates to align the couch with the isocenter, and providing visual or haptic guidance for precise positioning, either manually or automatically using electric motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual couch adjustment by operator is used, then positioning flexibility is maintained, but positioning time and operator workload increase significantly
Solution Approach 1:
The system performs self-positioning by automatically calculating the required couch displacement based on selected organ coordinates and executing the movement without operator intervention. The control unit autonomously determines the transformation between image coordinate systems and converts organ positions into couch displacement commands, enabling the system to service itself rather than requiring manual operator adjustment.
Solution Approach 2:
The patent replaces manual mechanical adjustment with an automated control system that uses coordinate transformation algorithms and electronic control signals. Instead of operators physically moving the couch based on visual estimation, the system substitutes mechanical manual operation with computational geometry and automated motor control to achieve precise positioning.
2Measurement precision
If multiple x-ray images are captured for position correction, then positioning accuracy improves, but radiation exposure and imaging time increase
Solution Approach 1:
The system performs preliminary coordinate system transformation and positioning calculation before actual imaging begins. By pre-calculating the optimal couch position based on the selected organ coordinates and transforming these into displacement commands, the system eliminates the need for iterative imaging and correction, achieving accurate positioning in a single setup action.
Solution Approach 2:
The patent introduces coordinate transformation as an intermediary step between image data and couch positioning. Instead of directly capturing multiple images for correction, the system uses mathematical coordinate transformation as a mediator to convert organ positions into precise couch displacement commands, thereby achieving accurate positioning without iterative imaging.
3Productivity
If automatic couch positioning is implemented, then positioning speed and accuracy improve, but system complexity increases
Solution Approach 1:
The control unit performs multiple functions: it processes image data, calculates coordinate transformations, determines organ positions, and generates couch displacement commands. By making the control unit universal and multi-functional, the system achieves automatic positioning without adding separate dedicated components for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent merges the coordinate transformation functionality with the existing control unit that manages couch movement. Instead of creating a separate positioning calculation system, the invention combines the mathematical transformation logic with the control unit's existing capabilities, merging multiple functions into a single integrated component to minimize system complexity.
Data Source
AI summary
For facilitating the optimal positioning of a patient resting on the couch of a C-arm computed tomography system, an input is received, via individual pixels or areas of pixels selected in a predetermined image data set, thus enabling the area of interest to be highlighted. Image data of the patient resting on the couch is acquired. These two processes together make it possible to calculate the position, relative to the couch, of a marked-out point that is to coincide with the isocenter for the rotation of the C-arm, and from this at least one coordinate that serves to define the position of the couch can be derived. If this coordinate is displayed, a doctor performing the treatment can move the couch to the appropriate position by hand. The couch can also be designed to be automatically movable by electric motors after determining the coordinate.