Ring Gantry Patient Support Rotation Near the Isocenter
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Solution Overview
Problem
Existing radiotherapy facilities face challenges in achieving precise patient positioning and rotation around the isocenter of the ring gantry due to conflicting requirements of stability and translational displacement, often using expensive and large rotary bearings that compromise positioning accuracy.
Innovation Solution
A medical treatment device design featuring a patient bed supported by proximal and distal bearing elements, allowing the intermediate element to rotate around a vertical axis positioned close to or at the isocenter, using a combination of guide and pivot bearings, and a scissor mechanism for height adjustment, enabling stable and cost-effective rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large diameter rotary bearing is used to ensure stability, then stability is improved, but the vertical axis is further from the isocenter causing greater translational displacement of the target volume
Solution Approach 1:
The patent divides the single large rotary bearing into two separate bearing elements (first and second bearing elements) with smaller diameters. These two elements work together to support the intermediate element's rotation, achieving both stability through the dual-element configuration and positioning accuracy by enabling the vertical axis to be located at or near the isocenter.
Solution Approach 2:
The patent introduces guide elements that work in conjunction with the two bearing elements. The guide elements constrain the motion of the bearing elements to ensure proper rotational guidance, mediating between the bearing elements and the intermediate element to achieve both stability and precise positioning around the isocenter.
2Manufacturing precision
If a small diameter rotary bearing is used to position the vertical axis at the isocenter, then positioning accuracy is improved, but stability is reduced
Solution Approach 1:
The patent combines two small-diameter bearing elements into a unified support system. While each individual bearing element has a small diameter that allows the vertical axis to be positioned at the isocenter, their combined configuration provides the necessary stability through distributed support and constraint.
Solution Approach 2:
The guide elements serve as intermediaries that connect the two small bearing elements to the intermediate element. They ensure that the small bearing elements work together effectively to provide both the precise positioning (by maintaining the vertical axis at the isocenter) and the required stability through proper force distribution and motion constraint.
3Device complexity
If guide structures are located only on one side of the ring gantry, then device complexity is reduced, but stability and positioning precision are compromised
Solution Approach 1:
The patent employs an asymmetric configuration where both bearing elements and guide elements are located on the same side of the ring gantry (the patient side). This asymmetric arrangement reduces device complexity compared to symmetric dual-side configurations while maintaining positioning reliability through the coordinated action of the two bearing elements and their associated guide elements.
Solution Approach 2:
The patent compensates for the single-sided location by utilizing the vertical dimension and the spatial relationship between the two bearing elements at different positions (proximal and distal). The first bearing element is positioned closer to the ring gantry while the second is farther away, creating a three-dimensional arrangement that provides both simplified structure and reliable positioning.
Data Source
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AI summary
A medical treatment device (1) comprises a ring gantry (2) designed as a stationary ring encircling a horizontal longitudinal direction (x) and having an isocenter (3). The medical treatment device (1) further comprises a patient table (4) positioned in front of the ring gantry (2) in the longitudinal direction (x) and comprising a base element (5), an intermediate element (6), a support (7), and a table board (8). The base element (5) is attached to the ring gantry (2) such that it is either not movable or only movable in a horizontal transverse direction (y) orthogonal to the longitudinal direction (x). The support (7) is arranged on the intermediate element (6), and the table board (8) is movable on the support (7) in a horizontal sliding direction (s) extending at least substantially in the longitudinal direction (x).The intermediate element (6) is supported on the base element (5) by means of a proximal and a distal bearing element (10, 11), the proximal bearing element (10) being located closer to the ring gantry (2) than the distal bearing element (11). Both bearing elements (10, 11) are located outside a volume enclosed by the ring gantry (2) and, viewed from the ring gantry (2), are located on the same side of the ring gantry (2). The intermediate element (6) is guided by at least one of the two bearing elements (10, 11) such that it rotates about a vertical axis (12). The vertical axis (12) lies either at the proximal guide element (10) or, viewed from the distal guide element (11), beyond it.