Particle Therapy Scan Timing for Interplay Effect Mitigation
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Solution Overview
Problem
Particle radiation therapy faces significant challenges in delivering precise doses to moving treatment targets due to the interplay effect, which leads to severe underdosage and overdosage, particularly in thorax and abdomen treatments, and is exacerbated by the inability to account for motion-induced dose perturbations with conventional methods.
Innovation Solution
A new scan technique that optimizes wait times and beam-on times to distribute spot repaintings evenly over the movement period of the target, allowing for superior mitigation of the interplay effect without the need for intra-treatment motion monitoring or synchronization, and can be implemented in existing particle radiation therapy centers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If particle PBS therapy is delivered with sequential scanning to achieve precise 3D dose shaping, then manufacturing precision is improved, but the interplay effect causes severe local underdosage and overdosage
Solution Approach 1:
The patent applies periodic action by delivering the particle beam in multiple repaintings that are synchronized with the periodic respiratory motion of the target. Each repainting is timed to occur at a specific phase of the respiratory cycle, creating a periodic delivery pattern that accounts for the target's motion. This ensures that the cumulative dose is distributed uniformly across the target volume over multiple breathing cycles, eliminating the interplay effect while maintaining precise 3D dose shaping.
2Productivity
If treatment is delivered in few fractions for SBRT to improve productivity, then productivity is improved, but the interplay effect becomes more serious causing pronounced underdosage and overdosage
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-planning the repainting sequence and timing before treatment delivery. The treatment plan is designed in advance to distribute the total dose across multiple repaintings that are synchronized with the target's motion pattern. This preliminary planning ensures that even when delivering high doses in few fractions, the dose is uniformly distributed across the moving target volume, eliminating the need for intra-treatment adjustments while maintaining dose precision.
3Ease of operation
If conventional methods are used to account for motion-induced dose perturbations by expanding safety margins, then ease of operation is improved, but the interplay effect cannot be adequately mitigated
Solution Approach 1:
The patent applies feedback by using real-time motion monitoring during treatment delivery to adjust the repainting timing and sequence. The system continuously monitors the target's position and motion, and this information is fed back to the beam delivery control system. Based on the feedback, the system dynamically adjusts when to deliver each repainting to ensure optimal synchronization with the target's motion, thereby accurately mitigating the interplay effect without requiring excessive safety margins.
Data Source
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AI summary
The present disclosure relates to a new scan technique for particle radiation therapy that may be used for cancer treatment. One embodiment relates to a method of mitigating interplay effect in particle radiation therapy in a moving target including a period of movement, where the particle radiation therapy defines a planned dose in each spot of each layer of the moving target. The method comprising dividing the planned dose in each spot into a number of spot repaintings; and generating a scan pattern for each layer by defining a beam-on time at each spot for each spot repainting, and calculating a wait time between consecutive beam-on times to distribute the spot repaintings for each spot of a respective layer are distributed over a duration of an integer number of periods of movement.