Pivoting Multileaf Collimator for Large Field Coverage
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Solution Overview
Problem
Conventional multileaf collimators (MLCs) face limitations in field shaping flexibility and cost due to leaf tip over-travel and carriage position constraints, which restrict their ability to effectively perform dynamic treatment techniques like IMRT and VMAT, particularly in achieving large, fully independent field sizes and volumes.
Innovation Solution
A carriageless MLC design with a pivoting mechanism that allows full overtravel and two degrees of freedom, enabling independent leaf tip positions and automatic field combining through treatment planning algorithms, thereby enhancing field shaping capabilities for larger field sizes and volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If leaf tips are extended far from carriage boxes to increase field size, then field shaping flexibility is improved, but leaf tip lateral position variance increases causing leaf gap leakage and collision risk
Solution Approach 1:
The MLC is divided into multiple carriage boxes, each independently controllable. This segmentation allows the system to achieve large field coverage through coordinated movement of multiple carriages rather than extending individual leaves excessively, thereby maintaining positioning precision while expanding field shaping capability.
Solution Approach 2:
The MLC implements dynamic carriage movement during treatment delivery. Carriages can move in and out of the treatment field dynamically, allowing the system to adapt leaf reach to the specific field size and shape requirements for each treatment segment, optimizing both field coverage and positioning accuracy.
2Manufacturing precision
If leaf tails are made very long to enable precise cantilevered extension, then leaf tip positioning precision is improved, but MLC weight and size increase leading to higher cost
Solution Approach 1:
The MLC is divided into multiple carriage boxes, each independently controllable. This segmentation allows the system to achieve large field coverage through coordinated movement of multiple carriages rather than extending individual leaves excessively, thereby maintaining positioning precision while expanding field shaping capability.
Solution Approach 2:
The MLC implements dynamic carriage movement during treatment delivery. Carriages can move in and out of the treatment field dynamically, allowing the system to adapt leaf reach to the specific field size and shape requirements for each treatment segment, optimizing both field coverage and positioning accuracy.
3Area of stationary object
If more leaves are added to increase field size coverage, then maximal field size is improved, but cost and device complexity increase while reliability decreases
Solution Approach 1:
The MLC implements dynamic carriage movement during treatment delivery. Carriages can move in and out of the treatment field dynamically, allowing the system to adapt leaf reach to the specific field size and shape requirements for each treatment segment, optimizing both field coverage and positioning accuracy.
Solution Approach 2:
Each carriage box is designed to be universally applicable for different field sizes and configurations. The same carriage design can handle various treatment scenarios by adjusting its position and the extent of leaf extension, reducing the need for specialized components for different field sizes.
4Device complexity
If conventional MLC carriage position limitations are maintained, then device simplicity is preserved, but instantaneous field shaping area is restricted to 15×40 cm2
Solution Approach 1:
The MLC implements dynamic carriage movement during treatment delivery. Carriages can move in and out of the treatment field dynamically, allowing the system to adapt leaf reach to the specific field size and shape requirements for each treatment segment, optimizing both field coverage and positioning accuracy.
Data Source
AI summary
A radiation apparatus includes a source operable to generate a radiation beam, a multileaf collimator operable to shape of the radiation beam, and a pivoting mechanism configured to pivot the multileaf collimator about the source. The radiation apparatus may further include a rotating mechanism configured to rotate the multileaf collimator about an axis passing through the source and the multileaf collimator.