Patient Platform Rotation Control for Particle Beam Therapy
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Solution Overview
Problem
Conventional radiation-therapy bed systems face challenges in efficiently positioning a patient's diseased site for particle beam therapy due to cumbersome adjustments required for non-conplanar irradiation, leading to prolonged treatment times and reduced throughput.
Innovation Solution
A driving type patient platform with translation and rotation units, controlled by a device that generates precise drive signals to align the patient's position and posture with treatment plan coordinates, ensuring the diseased site is positioned accurately and efficiently within the image capturing area of an X-ray device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional radiation-therapy bed systems are used for positioning, then the patient can be treated, but the positioning work takes a long time and throughput is reduced
Solution Approach 1:
The patent applies dynamics by enabling the patient platform to rotate around a virtual isocenter point rather than requiring complex multi-axis adjustments. The system dynamically calculates rotation angles and compensates for center point offsets, allowing the platform to adapt its orientation in a single rotational motion while maintaining precise positioning of the diseased site at the rotation center.
Solution Approach 2:
The patent replaces the conventional mechanical multi-axis adjustment system with a control-based rotational system. Instead of physically adjusting multiple axes to achieve positioning, the system uses computational geometry to calculate rotation parameters and controls a single rotational degree of freedom, substituting mechanical complexity with computational intelligence.
2Measurement precision
If the diseased site is monitored by X-ray while adjusting axes, then positioning can be performed, but the diseased site may fall outside the image capturing area requiring subtle adjustments
Solution Approach 1:
The patent introduces a virtual isocenter point as an intermediary reference that simplifies the positioning process. Instead of directly manipulating multiple axes while monitoring the diseased site, the system uses the virtual isocenter as a stable reference point and calculates all positioning adjustments relative to this center, making the operation more intuitive and reducing the risk of the site leaving the image area.
Solution Approach 2:
The system performs preliminary calculation of the virtual isocenter position and rotation parameters before executing the positioning operation. By pre-calculating the rotation angles and center point offsets based on the desired disease site position and the current platform state, the system prepares all necessary control signals in advance, ensuring accurate positioning without requiring complex real-time adjustments.
3Adaptability or versatility
If six degrees of freedom are provided for driving axes, then the diseased site can be moved to desirable position, but the adjustment work is extremely bothersome and time-consuming
Solution Approach 1:
The patent segments the complex six-degree-of-freedom positioning problem into a simpler rotational operation around a virtual isocenter. By dividing the positioning task into translation to the isocenter and rotation around it, the system reduces the control complexity while maintaining the ability to achieve any desired disease site position and orientation.
Solution Approach 2:
The system changes the parameter representation from six independent axis adjustments to two parameters: the virtual isocenter position and the rotation angle. This parameter transformation simplifies the control space while preserving the full positioning capability, as any desired disease site position can be achieved by appropriate selection of isocenter coordinates and rotation angle.
Data Source
AI summary
A patient platform for making the position and posture of a diseased site coincide with those established by a treatment plan. Translation units translate a top board in the X, Y and Z directions respectively, in a fixed coordinate system. Rotation units rotate the top board in the θ, φ, and ξ directions respectively. A controller controls the translation units and rotation units, based on desired rotation center point and desired rotation angle. The controller has a rotation drive signal generation unit that generates a signal for moving the top board in a rotating manner from the reference state “a” of the translation units and the rotation units to a desired rotation angle; and a translation drive signal generation unit that generates a signal for translating the translation units so the amount of translation movement, of the desired rotation center point, caused by the rotation movement is a predetermined value.