CAVMAT Radiotherapy Planning for Multiple Targets
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Solution Overview
Problem
Current radiosurgery techniques, such as single isocenter dynamic conformal arcs and volumetric modulated arc therapy, face challenges in accurately treating multiple targets due to limitations in inverse optimization, dosimetric accuracy, and complexity of multi-leaf collimator trajectories, leading to issues with dose distribution and tissue sparing.
Innovation Solution
The Conformal Arc Informed Volumetric Modulated Arc Therapy (CAVMAT) method, which involves assigning targets into subgroups for arc geometry, generating conformal arcs to maximize blocking, determining initial doses, and performing inverse optimization to adjust doses and conformity, allowing for flexible and complex-free MLC trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If single isocenter dynamic conformal arc (SIDCA) technique is used to reduce treatment time, then treatment time is reduced, but inverse optimization is lacking which reduces flexibility to modulate MLCs for irregularly shaped targets and proximity to critical structures
Solution Approach 1:
The patent segments the treatment approach into two phases: first generates conformal arc MLC trajectories without inverse optimization to maintain simplicity and reduce treatment time, then applies a limited inverse optimization process specifically tuned for conformal arcs to add necessary flexibility for irregular targets and critical structure protection, achieving both efficiency and adaptability
Solution Approach 2:
The patent implements a dynamic optimization process that adapts the MLC modulation based on the specific geometric constraints of each target and its relationship to critical structures, allowing the system to be simple when possible and more complex when necessary, rather than always using full inverse optimization
2Adaptability or versatility
If inverse optimized VMAT is used to provide flexibility for irregular shaped targets and minimize dose to OARs, then flexibility and target coverage are improved, but MLC trajectories become fast moving and highly modulated which negatively affects dosimetric accuracy
Solution Approach 1:
The patent changes the optimization parameters by developing a limited inverse optimization process specifically designed for conformal arcs rather than full VMAT optimization, adjusting the modulation depth and MLC velocity constraints to maintain dosimetric accuracy while achieving necessary flexibility for irregular targets and OAR protection
Solution Approach 2:
The patent applies partial inverse optimization rather than full optimization, using a simplified optimization process that provides just enough flexibility for irregular targets and critical structure protection without the excessive modulation that compromises dosimetric accuracy
3Productivity
If conformal arcs are used to treat multiple targets with a single isocenter, then treatment time is reduced compared to sequential multi-isocenter treatment, but targets overlapping with the same leaf pair cannot be eliminated entirely requiring complex tradeoffs
Solution Approach 1:
The patent segments targets into different arc groups where targets that overlap with the same leaf pair are separated into different arcs, allowing the MLC to fully block between targets in each arc while maintaining single-isocenter efficiency and avoiding excessive plan modulation complexity
Data Source
AI summary
Systems and methods are provided for single isocenter radiotherapy of multiple targets. Conformal arc information may be used in a Conformal Arc Informed Volumetric Modulated Arc Therapy (CAVMAT) method that includes single isocenter radiotherapy of multiple targets where conformal multi-leaf collimator (MLC) trajectories may be used as the starting point for limited inverse optimization. Single isocenter radiotherapy of multiple targets may provide flexibility with less complex MLC trajectories, and fully block between targets with the MLC.