Multi-Leaf Collimator Segmentation for Compact Nozzle Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In charged particle beam treatment apparatuses performing scanning irradiation, existing multi-leaf collimators increase the size of the irradiation nozzle by requiring space for leaf movement, which hinders the improvement of dose distribution at the peripheral edge of the irradiation field.
Innovation Solution
A charged particle beam treatment apparatus with a multi-leaf collimator where at least some leaves are shorter than half the length of the maximum scanning range, allowing for reduced space requirements and preventing nozzle size increase, along with optional blocking blocks and oscillating leaves for enhanced dose distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a multi-leaf collimator with full-length leaves is used to regulate the irradiation field shape, then the dose distribution at the peripheral edge is improved, but the irradiation nozzle size increases due to space requirements for leaf movement
Solution Approach 1:
The collimator leaves are segmented into multiple sections along the second axis, with each section having a length of less than half the maximum scanning range. This segmentation allows the leaves to achieve the necessary dose distribution control at the peripheral edge while reducing the overall space required for leaf movement, thereby preventing irradiation nozzle size increase.
Solution Approach 2:
The patent utilizes the scanning mechanism's movement along the first axis to compensate for the reduced leaf length in the second axis direction. By combining the scanning motion with the segmented leaf structure, the system achieves full irradiation field coverage without requiring full-length leaves, thus resolving the contradiction between dose distribution quality and nozzle size.
2Volume of moving object
If leaves are made shorter than half the maximum scanning range, then the space for leaf movement is reduced and nozzle size is maintained, but the ability to regulate the entire irradiation field may be compromised
Solution Approach 1:
The system dynamically combines the static segmented leaf structure with the dynamic scanning mechanism. The leaves remain stationary in the second axis direction with limited length, while the scanning mechanism provides dynamic movement along the first axis to achieve complete irradiation field coverage and shape regulation throughout the treatment process.
Solution Approach 2:
The segmented leaf structure is pre-configured with specific lengths and positions to optimize dose distribution at the peripheral edge. The scanning mechanism is pre-programmed with trajectories that coordinate with the leaf positions to ensure complete and accurate irradiation field regulation without requiring the leaves to physically cover the entire range.
Data Source
AI summary
A charged particle beam treatment apparatus includes an accelerator that generates and emits a charged particle beam, an irradiation nozzle that irradiates an irradiation target body with the charged particle beam, and a transport line that connects the accelerator and the irradiation nozzle to each other so as to transport the charged particle beam. The irradiation nozzle has a scanning unit which can scan the irradiation target body with the charged particle beam within a predetermined maximum scanning range in a direction along the first axis and a direction along the second axis, and a multi-leaf collimator disposed on a downstream side from the scanning unit, and which regulates a shape of an irradiation field when the irradiation target body is irradiated with the charged particle beam. The multi-leaf collimator has a pair of leaf groups disposed to face each other across the reference axis.