Multi-leaf collimator static guide actuation
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Solution Overview
Problem
Existing multi-leaf collimators in radiotherapy devices face inaccuracies in leaf positioning due to manufacturing tolerances and misalignment of leaf banks, leading to increased complexity and cost, particularly when using high-precision linear actuators and moving carriages.
Innovation Solution
A leaf bank actuator replaces the carriage to move the leaf bank as a unit relative to a static leaf guide, allowing more accurate and reliable lateral positioning of leaves, reducing the risk of misalignment and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-precision linear actuators and moving carriages are used to move leaf banks and leaves, then positioning accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The system separates the guidance function (static leaf guide) from the actuation function (leaf bank actuator and individual leaf actuators). The static leaf guide provides precise mechanical guidance without moving, while actuators provide motion. This segmentation allows high positioning accuracy through the rigid static guide while reducing overall system complexity by eliminating the need for complex moving carriage mechanisms.
Solution Approach 2:
Instead of using a moving carriage to carry and guide the leaves, the patent inverts the approach by using a static leaf guide that remains fixed while actuators move the leaf bank and individual leaves relative to it. This inversion eliminates the complexity of moving guidance structures while maintaining positioning accuracy through the stable static reference frame.
2Adaptability or versatility
If moving carriages are used to transport leaf banks, then flexibility in positioning is improved, but manufacturing precision deteriorates due to misalignment
Solution Approach 1:
The patent inverts the traditional approach by making the leaf guide static rather than moving with the carriage. This static reference frame provides a stable, precise alignment reference that does not suffer from carriage misalignment or manufacturing tolerances. The leaf bank and leaves move relative to this fixed guide, ensuring consistent alignment while maintaining positioning flexibility through actuator control.
Solution Approach 2:
The static leaf guide acts as an intermediary between the moving leaf bank/leaves and the fixed treatment isocenter. It provides a stable mechanical reference that mediates the relationship between the movable components and the fixed radiation beam axis, ensuring precise alignment without requiring the carriage itself to be perfectly aligned.
3Adaptability or versatility
If complex mechanisms with multiple moving parts are used, then positioning flexibility is improved, but reliability deteriorates due to accumulation of errors
Solution Approach 1:
The system segments the positioning function into independent components: the static leaf guide provides stable mechanical guidance, the leaf bank actuator moves the entire bank, and individual leaf actuators position specific leaves. This segmentation reduces the number of moving parts that must work together as a single complex mechanism, reducing error accumulation while maintaining positioning flexibility through coordinated actuation of independent components.
Solution Approach 2:
By inverting the approach and using a static leaf guide rather than a moving carriage, the patent reduces the number of moving parts and interfaces that can introduce errors. The static guide provides a reliable, error-free reference frame, while flexibility is achieved through controlled actuation of the leaf bank and leaves relative to this stable reference.
Data Source
AI summary
A multi-leaf collimator module for a radiotherapy device comprises: a leaf bank comprising a plurality of leaves. The module also comprises a leaf guide arranged to guide linear movement of the leaves in a first direction and a second direction opposite the first direction, the leaf guide being in direct contact with the leaves. The module further comprises a plurality of leaf actuators, each leaf actuator arranged to engender relative linear motion in the first direction and second direction between one leaf in the leaf bank and other leaves in the leaf bank; and a leaf bank actuator arranged to engender relative linear motion in the first direction and second direction between the entire leaf bank and the leaf guide.