Radiotherapy Planning for FLASH Dose Sequencing Near Organs at Risk
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Solution Overview
Problem
Existing radiotherapy methods cause undesired damage to healthy tissue due to lower dose rates, while FLASH therapy, with higher dose rates, reduces this damage but requires optimization to enhance its effect.
Innovation Solution
A computer-based method optimizes radiotherapy plans by delivering pencil beam spots in clusters with short time intervals to enhance the FLASH effect, using an optimization problem that penalizes low FLASH effect delivery orders and considers factors like RBE and spot placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional radiotherapy is delivered at lower dose rates, then the treatment can be administered with standard equipment and protocols, but healthy tissue suffers greater damage
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional dose rates (a few Gy per minute) to ultra-high dose rates (at least 40 Gy/s, typically 70 Gy/s). This fundamental change in the dose rate parameter enables FLASH therapy, which delivers the same therapeutic effect to tumors while significantly reducing damage to healthy tissue and organs at risk.
2Object-affected harmful factors
If FLASH therapy is delivered at ultra-high dose rates, then damage to healthy tissue is reduced by approximately 30%, but the dose delivery must be optimized to ensure sufficient FLASH effect in all irradiated volumes
Solution Approach 1:
The patent applies segmentation by dividing the treatment volume into multiple spots that are irradiated consecutively within short time intervals. The optimization method segments the dose delivery into discrete spot sequences, allowing control over the temporal structure to maintain FLASH conditions in all irradiated volumes while managing the complexity through systematic optimization.
Solution Approach 2:
The patent applies periodic action by delivering spots in a structured sequence with controlled time intervals. The optimization method implements periodic irradiation patterns where spots are delivered at regular, short intervals to maintain the FLASH effect throughout the treatment volume, transforming the complex continuous optimization problem into a manageable periodic delivery schedule.
3Device complexity
If spots are delivered with longer time intervals between them, then the delivery pattern is simpler, but the FLASH effect is reduced in volumes irradiated by spots delivered at different times
Solution Approach 1:
The patent applies preliminary action by pre-planning and optimizing the spot delivery sequence before treatment. The optimization method determines in advance the specific order and timing of spot delivery to ensure that all spots affecting a given volume are delivered within the FLASH time window, eliminating the need for complex real-time adjustments during treatment.
Data Source
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AI summary
A radiotherapy treatment planning method for achieving a FLASH radiotherapy treatment plan involves optimizing the plan using an optimization problem that has been designed to maximize the part of the irradiation that will be delivered under FLASH conditions, in particular to an organ at risk, to minimize the damage to the organ at risk.