IMAT Segment Redistribution for Arc Therapy Optimization
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Solution Overview
Problem
Traditional Intensity Modulated Radiation Therapy (IMRT) and Intensity Modulated Arc Therapy (IMAT) treatments face challenges in reducing treatment time and computational complexity due to 'dead time' during static beam delivery and the need for numerous beam angles, which increase workload and planning time.
Innovation Solution
The method involves determining and redistributing segments along an arc in IMAT treatment plans to optimize beam positions and reduce the number of segments at each position, using a computer-readable storage medium to execute instructions for repositioning and redistributing segments, thereby minimizing beam shaper motion and computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional static beam IMRT delivery is used with predetermined angles and segments, then treatment planning can be performed with standard methods, but dead time occurs during machine movement between angles extending treatment time
Solution Approach 1:
The patent transitions from static beam delivery at predetermined angles to dynamic arc therapy where the beam continuously rotates around the patient. The MLC leaves dynamically modulate the beam intensity during rotation, eliminating the need for stopping and starting between segments. This dynamic approach eliminates dead time while maintaining dose distribution accuracy through continuous optimization algorithms.
Solution Approach 2:
The patent implements continuous arc therapy where the radiation beam is delivered without interruption as the gantry rotates. The MLC leaves continuously adjust aperture shapes and positions throughout the arc, ensuring the beam is always on and delivering therapeutic dose. This continuous delivery eliminates the intermittent stopping characteristic of static IMRT, reducing treatment time while maintaining dosimetric quality.
2Manufacturing precision
If a large number of beam angles are used to achieve accurate dose distributions, then dose accuracy to tumors is improved, but workload and computational complexity of treatment planning increases
Solution Approach 1:
The patent transforms the treatment planning approach by changing from discrete angle selection to continuous arc parameter optimization. Instead of selecting specific beam angles, the system optimizes continuous parameters including arc start and end angles, rotation speed, MLC leaf positions, and dose rate modulation. This parameter transformation reduces the dimensionality of the optimization problem while maintaining dose distribution accuracy through mathematical modeling.
Solution Approach 2:
The patent replaces the mechanical approach of positioning the beam at discrete angles with a computational optimization system that calculates optimal continuous arc trajectories. The treatment planning software uses algorithms to determine the ideal beam path and MLC configurations, substituting iterative mechanical angle adjustments with direct computational solution of the optimization problem, thereby reducing planning complexity.
3Productivity
If MLC leaf travel is reduced to shorten treatment time, then treatment delivery speed increases, but dose distribution accuracy may be compromised
Solution Approach 1:
The patent performs preliminary optimization calculations during the treatment planning phase to determine the optimal MLC leaf positions and aperture shapes for each point along the arc. The system pre-calculates the entire treatment trajectory and MLC motion paths, ensuring that leaf travel is minimized while maintaining dose accuracy. This preliminary optimization allows the treatment delivery to proceed efficiently without real-time complex calculations.
Solution Approach 2:
The patent employs dynamic MLC modulation where the leaves continuously adjust their positions during arc rotation to maintain optimal aperture shapes. The system dynamically optimizes leaf trajectories to minimize total travel distance while ensuring accurate dose delivery through real-time intensity modulation. This dynamic approach allows reduced leaf travel compared to static IMRT while maintaining dosimetric quality through continuous adaptation.
Data Source
AI summary
A treatment planner (102) generates fluence maps (140) indicative of a desired fluence distribution at various locations (304, 312) along a treatment arc (302). A converter (142) converts the fluence distributions (140) to treatment device settings (144). The settings (144) may include multiple segments. A segment distributor (146) distributes the settings to locations in the vicinity of their original positions.