Dynamic Segmentation for Orthogonal Double-Layer Grating Blades
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Solution Overview
Problem
Dynamic segmentation of orthogonal double-layer gratings in radiotherapy faces challenges due to coupled blade motions, increasing the complexity of segmentation algorithms and requiring more MU, while existing methods lack efficient implementation strategies.
Innovation Solution
A dynamic intensity-modulated segmentation method using a sliding-window approach, where a virtual single-layer grating is constructed by synthesizing the velocities of orthogonal double-layer grating blades, allowing for independent segmentation calculations, and optimizing blade motion trajectories and segment weights to improve conformity and irradiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dynamic segmentation is applied to orthogonal double-layer gratings, then irradiation efficiency and dose curve steepness are improved, but blade motion coupling increases algorithm complexity and requires more MU
Solution Approach 1:
The patent divides the complex dynamic segmentation problem into independent subfields, where each subfield can be calculated independently. This segmentation approach reduces the overall algorithm complexity by breaking down the coupled blade motion problem into manageable independent units that can be processed separately and then combined.
Solution Approach 2:
The patent introduces an intermediary calculation model that decouples the blade motion equations, allowing independent calculation of segmentation parameters for each blade pair. This intermediary approach transforms the complex coupled system into a form where standard segmentation algorithms can be applied independently to each subfield.
2Manufacturing precision
If orthogonal double-layer gratings are used, then conformity in blade thickness direction is improved, but blade motion coupling makes segmentation algorithm implementation difficult
Solution Approach 1:
The patent segments the treatment field into multiple independent subfields, each corresponding to a specific blade pair configuration. This segmentation allows the complex orthogonal double-layer grating problem to be solved through multiple simple independent calculations rather than one complex coupled calculation.
Solution Approach 2:
The patent transforms the problem from a coupled two-dimensional blade motion space into independent one-dimensional segmentation problems for each blade pair. By treating each blade pair's motion independently in its own dimension, the algorithm implementation becomes tractable while maintaining the three-dimensional conformal dose distribution.
3Measurement precision
If more MU are used to complete dynamic segmentation, then segmentation precision is improved, but treatment time increases
Solution Approach 1:
The patent performs preliminary calculation of optimal segmentation parameters and blade trajectories before actual treatment delivery. By pre-calculating the segmentation plan with high precision using the independent subfield method, the actual treatment can be executed efficiently without requiring excessive MU or time during delivery.
Data Source
AI summary
The invention discloses a dynamic intensity-modulated segmentation method for an orthogonal double-layer grating blade device. The core of the segmentation algorithm is to construct a virtual single-layer grating after the velocities of the two-layer gratings are synthesized to perform dynamic intensity modulation of the single-layer grating (sliding-window) segmentation, and finally use two layers of gratings to conform to each segment. In order to reduce the segmentation error, the invention provides two optimization methods: blade motion trajectory optimization method and segment weight optimization method. The blade motion trajectory optimization method is to optimize the objective function under certain constraints with the motion trajectory of each blade as a variable under the condition that the segment weight is fixed. Segment weight optimization method is to optimize the time points of each segment when the blade motion trajectory is fixed. Both of the two optimization methods can reduce the error of the segmentation intensity and improve the optimization effect.