Couch Motion Tracking via Marker Coordinate Conversion
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Solution Overview
Problem
Current methods for evaluating the motion of a couch in particle beam treatment apparatuses, such as using graphic paper, lasers, or goniometers, are prone to errors due to visual determination, making precise position control challenging, especially for radiation-sensitive patients.
Innovation Solution
A motion evaluation system utilizing a marker member with a body part having parallel surfaces, reference indication, and markers, along with cameras to generate and convert coordinate values between coordinate systems, enabling accurate motion tracking and conversion of object motion into a treatment room coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If visual determination methods (graphic paper, laser, goniometer) are used to evaluate couch motion, then the evaluation process is simple and easy to operate, but the measurement precision is low and erroneous results occur
Solution Approach 1:
The patent replaces visual determination methods with an optical measurement system consisting of markers attached to the couch and cameras to capture marker positions. This substitution of mechanical/visual methods with optical detection enables precise automated measurement of couch motion without relying on human visual judgment, thereby resolving the contradiction between ease of operation and measurement precision
Solution Approach 2:
The patent introduces markers as intermediary objects attached to the couch surface. These markers serve as mediators between the couch motion and the camera detection system, enabling precise optical tracking of couch position and movement. The markers translate physical couch motion into detectable optical signals, achieving high measurement precision while maintaining operational simplicity
2Reliability
If precise couch position control is implemented to prevent radiation damage to organs, then the reliability of treatment is improved, but the device complexity increases due to multiple coordinate systems and conversion requirements
Solution Approach 1:
The patent establishes a multi-functional coordinate conversion system that handles multiple coordinate systems (camera coordinate system, treatment room coordinate system, couch coordinate system) through a unified conversion methodology. The conversion module serves multiple purposes: transforming marker positions, calculating couch motion, and enabling precise positioning control, thereby improving reliability without proportionally increasing device complexity
Solution Approach 2:
The patent creates a virtual coordinate representation of the physical couch and treatment environment through coordinate system modeling. By copying spatial relationships into mathematical coordinate systems and enabling transformations between them, the system achieves precise motion control and reliability without requiring complex physical modifications to the actual treatment apparatus
3Measurement precision
If multiple cameras are used to generate coordinate images of markers, then the measurement precision of couch motion is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs multiple cameras positioned at different spatial locations to capture marker positions from different viewing angles. This multi-dimensional approach enables three-dimensional reconstruction of couch motion by combining two-dimensional image data from multiple cameras, achieving high measurement precision while distributing the complexity across multiple simple camera units rather than requiring a single complex measurement device
Data Source
AI summary
A motion evaluation system includes a marker member including a body part having a first surface and a second surface parallel to the first surface, a reference indication part indicating a center of the first surface, and a plurality of markers arranged on the first surface to be spaced apart from the reference indication part. The marker member is arranged on an object such that the reference indication part is arranged at a reference point of a first coordinate system. A plurality of cameras generate coordinate images by respectively photographing the markers. A first coordinate calculator calculates first coordinate values of the markers in a first coordinate system by using separation distances of the markers and a first distance between the first surface and the second surface, the separation distances and the first distance being previously stored. A second coordinate calculator calculates second coordinate values of the markers in a second coordinate system by using the coordinate images generated by the cameras. A coordinate converter produces a conversion relationship between the first coordinate system and the second coordinate system by using the first coordinate values and the second coordinate values of the markers, and converts second motion information in the second coordinate system corresponding to a motion of the object objected by using the cameras to first motion information in the first coordinate system.