Radiotherapy Table Positioning With Tilt-Rotation Target Alignment
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Solution Overview
Problem
Current patient-positioning systems for radiotherapy lack the ability to accurately account for the rotation and tilt angles of the patient table, leading to inaccuracies in locating the irradiation target when patients are positioned in postures other than supine.
Innovation Solution
A patient-positioning system that includes a processing device and storage device, with modules to calculate and adjust the tilt and rotation angles of the patient table using image registration and mechanical devices to align the irradiation target with the beam exit, utilizing camera devices and laser emitters for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the patient table is tilted or rotated to irradiate patients in various postures, then the adaptability of the radiotherapy system is improved, but the positioning accuracy of the irradiation target deteriorates
Solution Approach 1:
The system performs preliminary calculations in the positioning room before actual treatment. It pre-calculates the fulcrum displacement based on the desired tilt angle and rotation angle, then uses this information to accurately position the patient table before irradiation begins. This preliminary positioning action ensures that when the table is tilted or rotated for various postures, the irradiation target remains accurately positioned.
Solution Approach 2:
The system uses camera devices to capture the actual position of the patient's body surface characteristics and compares this with the planned position. The image registration module calculates the offset between actual and planned positions, and the control module adjusts the fulcrum displacement accordingly to correct any positioning deviations before irradiation occurs.
2Adaptability or versatility
If the patient table is tilted at large angles to achieve various irradiation postures, then the versatility of the system is improved, but the complexity of the positioning calculation increases
Solution Approach 1:
The positioning calculation is segmented into independent modular components: a positioning room module that calculates fulcrum displacement based on tilt angle, a treatment room module that handles rotation angle calculations, and an image registration module that processes camera data. This segmentation allows each module to handle specific calculations independently, reducing overall system complexity while supporting versatile irradiation postures.
Solution Approach 2:
The system introduces an intermediary coordinate transformation model that bridges the relationship between the original supine position coordinates and the tilted/rotated position coordinates. This intermediary mathematical model simplifies the complex spatial transformation by providing a systematic method to convert between different posture configurations, making the positioning calculation more manageable.
3Measurement precision
If image registration is performed to calculate fulcrum displacement for precise positioning, then the positioning accuracy is improved, but the time required for positioning increases
Solution Approach 1:
The positioning room module performs preliminary calculations of fulcrum displacement based on the desired tilt angle and rotation angle before the actual image registration process. By pre-calculating the expected fulcrum position and using this information to guide the image registration, the system reduces the time needed for actual positioning adjustments while maintaining high accuracy.
Solution Approach 2:
The system replaces complex mechanical positioning adjustments with computational methods. Instead of relying solely on physical trial-and-error positioning, the system uses image registration algorithms and mathematical models to calculate the precise fulcrum displacement, thereby reducing the time required for physical positioning adjustments while improving measurement accuracy.
Data Source
AI summary
A patient-positioning system for radiotherapy is provided. The system includes a processing device and a storage device. The processing device loads a program from the storage device to execute a control module, a positioning room module, and a treatment room module. The control module obtains treatment planning data. The positioning room module calculates the second support displacement of the fulcrum through image registration based on the tilt angle, rotation angle, target displacement, original target point cloud, and a reference displacement. The treatment room module drives the mechanical device to move the treatment room table such that the fulcrum is at the second support displacement relative to the beam exit.