Particle Therapy Beam Intensity Control for Spot and Continuous Irradiation
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Solution Overview
Problem
Existing particle therapy systems face challenges in determining optimal beam intensity when both discrete spot irradiation and continuous beam irradiation coexist, leading to trade-offs between irradiation time and dose distribution, with potential deterioration in dose distribution due to discretization delays.
Innovation Solution
A treatment planning system that includes a spot determination unit dividing the irradiation region into layers and a beam intensity determination unit evaluating and adjusting beam intensity to minimize irradiation time while maintaining dose distribution, by setting conditions for change in dose distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beam intensity is increased to reduce irradiation time, then productivity is improved, but the number of discretized spots increases and dose distribution deteriorates
Solution Approach 1:
The patent changes the parameter of beam intensity dynamically across different layers. By adjusting beam intensity per layer based on spot density and distance from reference points, the system achieves optimal balance between irradiation time and dose distribution without requiring uniform high intensity throughout, thus resolving the contradiction between productivity and precision.
Solution Approach 2:
The patent applies different beam intensity levels to different regions (layers) of the irradiation target. Layers with higher spot density or greater distance from reference points receive adjusted intensity levels, creating local quality variations that optimize both treatment efficiency and dose distribution uniformity, thereby resolving the global trade-off between irradiation time and dose precision.
2Manufacturing precision
If beam intensity is decreased to reduce the number of discretized spots, then dose distribution is improved, but irradiation time is increased
Solution Approach 1:
Rather than uniformly decreasing beam intensity, the patent dynamically adjusts intensity parameters per layer based on local spot density and geometric relationships. This allows the system to maintain low discretization (good dose distribution) while compensating for reduced intensity through selective optimization, thus avoiding the penalty of increased irradiation time.
Solution Approach 2:
The patent introduces dynamic adjustment of beam intensity based on real-time calculation of spot density and distance metrics. This dynamic approach allows the system to adapt intensity levels to local conditions, achieving good dose distribution without uniformly reducing intensity across all spots, thereby maintaining acceptable irradiation time while improving dose precision.
3Manufacturing precision
If discrete spot irradiation is used to improve dose distribution control, then manufacturing precision is improved, but device complexity increases due to beam on-off switching
Solution Approach 1:
The patent applies discrete spot irradiation selectively to specific layers based on local spot density and distance from reference points, rather than uniformly across all layers. This localized application of discrete irradiation reduces the overall frequency of beam on-off switching while maintaining dose distribution control where most needed, thus reducing control system complexity while preserving precision benefits.
Solution Approach 2:
The patent uses discrete spot irradiation partially - only in layers where it provides significant benefit according to the calculated spot density and distance criteria. In other layers, continuous or different irradiation patterns may be used, avoiding unnecessary beam switching operations and reducing overall system complexity while maintaining adequate dose control.
Data Source
AI summary
There is provided a treatment planning system and a particle therapy system. In the related art, it is unable to determine optimum beam intensity in irradiation for which discrete spot irradiation and continuous beam irradiation coexist. There is provided a treatment planning system that includes a spot determination unit that divides an irradiation region to be irradiated with a charged particle beam into a plurality of layers in an advancing direction of the charged particle beam and disposes a plurality of irradiation spots, which becomes irradiation points of the charged particle beam, in the layers and a beam intensity determination unit that determines beam intensity for each of the layers by evaluating the irradiation time by changing the beam intensity in a range of a condition of change in dose distribution which is set in advance.