Orthogonal Double-Layer Collimators for IMAT Dose Conformity
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Solution Overview
Problem
Current rotation intensity modulation technologies using single-layer or parallel double-layer gratings face limitations in conforming to varying tumor thickness and require multiple subfields and arcs, leading to inefficient treatment due to restricted blade movement and complexity in irradiation intensity.
Innovation Solution
The method employs orthogonal double-layer multi-leaves collimators, discretizing the rotating arc into equally spaced fields, calculating field intensity matrices using the conjugate gradient method, and applying a double-layer grating static segmentation algorithm to optimize subfields, followed by genetic algorithm and Monte Carlo dose calculations to improve dose distribution and treatment efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-layer grating is used for rotation intensity modulation, then the device structure is simple, but the blade can only move in one direction and its ability to conform to the thickness direction of the blade is limited
Solution Approach 1:
The patent transitions from a single-layer grating to a double-layer grating structure, adding another dimension of blade movement. The first layer of blades moves in a first direction while the second layer of blades moves in a second direction orthogonal to the first direction, enabling conformal modulation in multiple directions simultaneously
2Manufacturing precision
If parallel double-layer grating is used, then the blade thickness direction is improved, but it is limited by the blade thickness and can not move or form an irradiation unit at any position
Solution Approach 1:
The patent implements dynamic blade movement in both layers, where the first layer of blades moves in a first direction and the second layer of blades moves in a second direction orthogonal to the first direction. This dynamic configuration allows the system to adapt blade positions to form irradiation units at various locations and orientations, overcoming the positioning limitations of static parallel double-layer gratings
3Manufacturing precision
If single-layer grating or parallel double-layer grating is used for complex irradiation intensity, then multiple subfields are required, but multiple irradiation arcs are needed and treatment efficiency is reduced
Solution Approach 1:
The patent merges the functionality of multiple subfields and irradiation arcs into a single integrated double-layer grating system. By coordinating the movement of both layers of blades, the system can achieve complex irradiation intensity patterns that would otherwise require multiple separate subfields and arcs, thereby improving treatment efficiency
Data Source
AI summary
The invention provides a method and device for IMAT using orthogonal double layer multi leaves collimators. The method includes: discretizing the rotating arc into multiple equally spaced fields; using the conjugate gradient method to calculate the field intensity matrix; using the double-layer grating static segmentation algorithm to calculate the subfields of each field to obtain the first predetermined number of subfields with the largest contribution to the field of each field; selecting two subfields with similar shapes from the first predetermined number of subfields with the largest contribution, distributing them to the arc of rotation, and performing interpolation to obtain discrete subfields; calculating deposition Matrix; iterative calculation of the shape and weight of subfield; using Monte Carlo dose algorithm to calculate the intensity-modulated dose distribution.