Dynamic Collimator Rotation for VMAT Resolution
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Solution Overview
Problem
Volumetric modulated arc therapy (VMAT) systems face limitations in achieving high resolution and flexibility due to mechanical constraints of multileaf collimators (MLCs), leading to compromises between resolution and field of view size, which affects treatment efficiency and consistency.
Innovation Solution
A novel optimization framework incorporating dynamic collimator rotation is introduced to generate optimized VMAT plans, using an objective function that accounts for collimator rotation, allowing for increased resolution without the need for costly collimator upgrades or replacements, by employing an iterative optimization process and a Primal Dual Hybrid Gradient algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MLC leaves are made narrower to increase resolution, then manufacturing difficulty increases and field of view size is reduced
Solution Approach 1:
The patent applies dynamic collimator rotation during the VMAT arc delivery, allowing the collimator to rotate independently from the gantry. This dynamic adjustment enables the system to achieve variable effective leaf widths throughout the treatment arc, providing high resolution where needed without requiring permanently narrow leaves that would limit field of view and increase manufacturing complexity
Solution Approach 2:
The system changes the effective collimator resolution parameter dynamically during treatment by rotating the collimator to different angles. This allows the same physical MLC leaves to provide different effective resolutions at different beam angles, achieving high resolution without permanently narrowing the leaves, thereby avoiding manufacturing difficulties and field of view reduction
2Measurement precision
If MLC leaves are made narrower to increase resolution, then field of view size is reduced
Solution Approach 1:
By implementing dynamic collimator rotation during VMAT arc delivery, the system can achieve variable effective leaf widths throughout the treatment arc. This allows high resolution to be achieved at specific angles without permanently narrowing the MLC leaves, thereby maintaining a large field of view for patient positioning and treatment delivery
Solution Approach 2:
The system dynamically changes the effective collimator resolution parameter during treatment by rotating the collimator to different angles. This allows the same physical MLC configuration to provide different effective resolutions, achieving high resolution where needed while maintaining a large field of view for overall treatment delivery
3Measurement precision
If multiple arcs are used to achieve satisfactory dose distributions, then treatment time and monitor units increase
Solution Approach 1:
The patent implements dynamic collimator rotation during a single VMAT arc delivery, allowing continuous adjustment of the collimator angle throughout the arc. This dynamic control enables satisfactory dose distributions to be achieved in a single arc rather than requiring multiple arcs, thereby reducing treatment time and monitor unit consumption while maintaining dose distribution quality
Solution Approach 2:
The system dynamically changes the collimator rotation parameter during VMAT arc delivery to optimize dose distribution. This allows a single arc to achieve the same dose distribution quality that would traditionally require multiple arcs, reducing treatment time and monitor units while maintaining precision
Data Source
AI summary
Systems and method for generating and executing volumetric modulated arc therapy (“VMAT”) plans are provided. In some aspects, the method includes receiving a representation of a subject comprising information related to target and non-target volumes of interest, and generating an objective function based on the representation of the subject, wherein the objective function accounts for dynamic collimator rotation. The method also includes performing an iterative optimization process, using the objective function, to generate a dynamic collimator VMAT plan, and generating a report in accordance with the dynamic collimator VMAT plan.