Binary MLC Per-Leaf Field Width for Beam Conformality
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Solution Overview
Problem
Conventional binary multileaf collimator (MLC) systems are limited in conforming radiation treatment beam fields to target regions with non-uniform shapes, particularly along the length, due to constant superior-inferior field width, which restricts field sizes to less than 5cm and increases radiation exposure to non-target regions.
Innovation Solution
The implementation of a high-speed MLC, such as an electromagnetic MLC, that allows for dynamic leaf motion to modulate fluence not only in the IEC-Xb direction but also in the IEC-Yb direction and longitudinally, enabling larger field sizes and more precise conformality to target profiles while minimizing exposure to non-target areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional binary MLC systems use constant superior-inferior field width, then device simplicity is maintained, but field size is limited to less than 5cm and conformality to non-uniform target regions deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from constant field width to variable field width. The MLC system dynamically adjusts the superior-inferior field width along the longitudinal direction, allowing each leaf pair to operate at different widths. This dynamic adjustment enables the beam field to conform to non-uniform target regions while maintaining binary MLC system simplicity.
Solution Approach 2:
The patent implements local quality by allowing different portions of the MLC to have different field widths. Each leaf pair can be independently configured with its own superior-inferior field width, enabling local optimization of beam conformality to match the specific geometry of target regions at different locations along the treatment volume.
2Ease of operation
If conventional binary MLC systems maintain constant field width, then operational simplicity is preserved, but treatment efficiency deteriorates due to limited field sizes requiring multiple smaller fields
Solution Approach 1:
The system maintains operational simplicity through automated dynamic adjustment. The MLC controller automatically varies the field width along the longitudinal direction without requiring complex manual intervention, preserving ease of operation while enabling larger field sizes that improve treatment efficiency by reducing the number of fields needed.
Solution Approach 2:
The patent changes the field width parameter dynamically along the longitudinal direction. By varying this key parameter, the system achieves larger effective field sizes and improved treatment efficiency while maintaining binary MLC operational simplicity through automated parameter control.
3Reliability
If conventional binary MLC systems use fixed field width, then system reliability is maintained, but radiation exposure to non-target regions increases due to inability to conform to complex target shapes
Solution Approach 1:
The patent reduces radiation exposure to non-target regions by applying local quality principles. Each leaf pair is configured with its own optimized field width, allowing the beam to precisely conform to the target region's geometry at each location. This local optimization minimizes radiation spillage into surrounding healthy tissues while maintaining system reliability through controlled binary operation.
Solution Approach 2:
The dynamic adjustment of field width along the longitudinal direction enables the system to adapt to complex target shapes, improving conformality and reducing radiation exposure to non-target regions. The binary MLC system maintains reliability through automated dynamic control that precisely manages beam geometry throughout the treatment volume.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the MLC to effectively shape radiation beams to conform to complex target regions, allowing for larger field sizes, faster treatment times, and more opportunities for intensity modulation, thereby reducing radiation exposure to non-target areas and improving treatment efficiency.
Implementation Method 1
The implementation of a high-speed MLC, such as an electromagnetic MLC, that allows for dynamic leaf motion
Data Source
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AI summary
A radiation treatment delivery system, includes a linear accelerator (LINAC) and a multileaf collimator (MLC), coupled with the distal end of the LINAC, wherein the MLC has two banks of leaves, organized into a plurality of opposing leaf pairs. The system further includes a processing device, operatively coupled to the LINAC and the MLC, to control the plurality of leaf pairs of the MLC such that for each of a plurality of radiation beam delivery positional sections corresponds to a range of radiation beam positions over a discrete time interval, wherein each leaf pair of the plurality of opposing leaf pairs is open to a fixed opening for a fraction of time in the discrete time interval and closed for the remaining fraction of time in the discrete time interval, while a radiation beam of the radiation treatment system is active.