Dynamic MLC Leaf Control for Moving Target Radiotherapy
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Solution Overview
Problem
Current radiation therapy techniques face challenges in delivering precise doses to moving targets due to interplay between target movement and multi-leaf collimator (MLC) movements, leading to variations in delivered dose distributions, with existing methods either under or over-irradiating the target.
Innovation Solution
A method and system for performing intensity modulated radiotherapy (IMRT) that involves developing treatment plans with sub-plans based on anticipated target positions, incorporating real-time tracking of target movement to adjust MLC leaf positions, and using predicted target positions to facilitate smooth transitions between sub-plans, ensuring accurate dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If radiation therapy is delivered using MLC to shape the beam conformally to the target, then the precision of dose delivery to the target is improved, but the system becomes sensitive to target movements during treatment
Solution Approach 1:
The patent implements dynamic treatment delivery where the MLC leaves move continuously during radiation delivery rather than remaining static. This dynamic approach allows the treatment system to adapt to target movements by adjusting leaf positions in real-time, maintaining dose accuracy despite anatomical changes during treatment
Solution Approach 2:
The system incorporates real-time tracking of target position and uses this feedback information to adjust MLC leaf positions dynamically. By monitoring target movement and responding with compensatory leaf adjustments, the system maintains precise dose delivery to the moving target while preserving treatment consistency
2Adaptability or versatility
If the MLC leaves are moved continuously during radiation delivery (sliding window approach), then the intensity distribution control is improved, but the interplay between leaf movement and target movement causes dose distribution variations
Solution Approach 1:
The system uses real-time feedback from target tracking to dynamically adjust MLC leaf positions during sliding window delivery. This feedback mechanism compensates for the interplay effects between leaf movement and target movement, maintaining accurate dose distribution while preserving the intensity modulation capabilities of the sliding window approach
Solution Approach 2:
The patent dynamically changes the parameters of MLC leaf positions and movement speeds in response to real-time target position data. By adjusting these parameters adaptively, the system maintains precise dose delivery despite the continuous movement of both leaves and target, resolving the interplay problem while preserving intensity control versatility
3Productivity
If higher radiation doses are delivered to the target over shorter time spans, then the treatment efficiency is improved, but the requirement for precise target positioning becomes more critical
Solution Approach 1:
The system employs dynamic MLC leaf movement that can adapt to target position changes in real-time, enabling shorter treatment times without sacrificing precision. The dynamic adjustment capability allows the system to maintain accurate dose delivery even when treatment duration is reduced, thus improving efficiency while meeting precision requirements
Solution Approach 2:
Real-time target tracking provides continuous feedback that enables the system to maintain precise positioning accuracy throughout the treatment process. This feedback mechanism allows for shorter treatment times by eliminating the need for excessive safety margins and repositioning time, thereby improving efficiency while preserving positioning precision
Data Source
AI summary
A method and system for providing intensity modulated radiation therapy to a moving target is disclosed. According to a preferred embodiment of the invention, a treatment plan for providing radiotherapy using a multi-leaf collimator (“MLC”) comprises a plurality of sub-plans, each of which is optimized for a different phase of target movement. Movements of the treatment target are tracked in real time, and the choice of which sub-plan to implement is made in real time based on the tracked position of the target. Each of the sub-plans is preferably formulated to minimize interplay effects between target movements and MLC leaf movements, consistent with other planning goals. In addition, the sub-plans preferably include a predicted region corresponding to the next anticipated position of the target, in order to facilitate the transition to the next position.