Segmented VMAT Arc Delivery for Breath-Hold Coordination
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Solution Overview
Problem
Current VMAT systems take longer than a single tolerable breath hold to deliver each arc, leading to inefficiencies and inaccuracies due to respiration-induced organ motion, particularly in Elekta's VMAT technology where breath-hold timing is less predictable.
Innovation Solution
The system and method involve dividing the VMAT arc into segmented short-arcs, each lasting less than a breath-hold interval, with specific control points and monitor units distribution to ensure continuous dose delivery across segments, allowing for precise dose planning and delivery within breath-hold limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If VMAT arc delivery is performed using conventional methods, then dose coverage is improved, but delivery time exceeds breath-hold interval causing organ motion uncertainty
Solution Approach 1:
The VMAT arc is divided into multiple segments, each delivering a portion of the total dose. This segmentation allows the total delivery time to be distributed across multiple breath-hold intervals, ensuring each individual segment completes within a single breath-hold while maintaining overall dose coverage through cumulative effect.
2Loss of time
If VMAT arc is divided into segmented short-arcs, then delivery time is reduced to fit breath-hold interval, but system complexity increases
Solution Approach 1:
The arc is segmented into multiple short-arcs that can be delivered within individual breath-hold intervals. This segmentation reduces the delivery time of each segment to fit within breath-hold constraints while managing system complexity through structured planning and delivery protocols.
Solution Approach 2:
The VMAT plan is pre-segmented into short-arcs with predetermined control points and monitor unit distributions before treatment delivery. This preliminary segmentation and planning allows the treatment system to execute pre-calculated segments within breath-hold intervals, reducing real-time complexity during actual delivery.
3Reliability
If segmented short-arcs are used with breath-hold coordination, then breath-hold coordination is enhanced, but dose delivery continuity becomes more difficult to maintain
Solution Approach 1:
Control points and monitor units are pre-distributed across segmented short-arcs during treatment planning, ensuring that each segment is self-contained with all necessary delivery parameters. This preliminary configuration maintains dose delivery continuity by pre-establishing the sequence and dosimetric properties of each segment.
Solution Approach 2:
The segmented short-arcs are designed to collectively deliver the complete prescribed dose through cumulative effect. Each segment contributes to the overall continuous dose distribution, maintaining therapeutic effectiveness despite intermittent delivery pauses between breath-holds.
Data Source
AI summary
The invention designs the segmented short-arc VMAT plan, modified from the original long-arc VMAT, to fit the breath-hold interval. The modified VMAT of the invention has the advantages of its applicability to different planning systems for variously long arcs and its preprogrammed arc segmentation for summated dose consistency. Using segmented short-arc modification from the original long-arc VMAT plan is accurate for dose planning and delivery, as well as tolerable for breath-hold VMAT.