Particle Therapy Scan Path Optimization for Collimator Aperture
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Solution Overview
Problem
Current particle therapy systems for cancer treatment face inefficiencies in scan path length and treatment time due to irradiation of areas outside the collimator aperture, leading to increased beam loss and prolonged treatment times in uniform scanning and conformal layer stacking irradiation methods.
Innovation Solution
A treatment planning apparatus determines optimized charged particle beam scan paths that minimize irradiation of areas outside the collimator aperture by calculating collimator aperture shapes and scan paths based on X-ray CT images, allowing for uniform dose distribution within the aperture area, and adjusts scan paths and collimator apertures for each layer in conformal layer stacking irradiation to reduce unnecessary irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charged particle beam is scanned over the entire irradiation field area in uniform scanning, then the dose distribution uniformity is achieved, but the scan path length increases and beam loss increases
Solution Approach 1:
The patent applies local quality by determining that different regions of the irradiation field require different scan path lengths. Specifically, the scan path is optimized to cover only the collimator aperture area where the beam is actually delivered, rather than scanning the entire irradiation field. This is achieved by calculating the collimator aperture shape from patient CT data and using that to define the precise scan boundaries, thereby reducing beam loss in regions outside the aperture while maintaining uniform dose distribution within the aperture.
2Reliability
If the charged particle beam is scanned over the entire irradiation field area, then the dose distribution uniformity is achieved, but the treatment time increases
Solution Approach 1:
The patent determines that the scan path should be localized to the collimator aperture area rather than covering the entire irradiation field. By calculating the precise aperture shape from patient CT data and using that to define scan boundaries, the system reduces unnecessary scanning time in regions outside the aperture while maintaining uniform dose distribution within the aperture, thereby reducing overall treatment time.
3Device complexity
If a fixed scan path is used for all layers in conformal layer stacking irradiation, then the system complexity is reduced, but the beam utilization efficiency decreases due to irradiation of areas outside the collimator aperture
Solution Approach 1:
The patent applies dynamics by making the scan path adaptive to each layer's collimator aperture shape. Instead of using a fixed scan path for all layers, the system calculates the specific aperture shape for each layer from patient CT data and determines the optimal scan path for that layer. This dynamic adjustment of scan paths per layer reduces beam loss in regions outside the aperture while maintaining manageable system complexity through automated calculation.
4Reliability
If the collimator aperture is reduced for proximal layers in conformal layer stacking irradiation, then the dose distribution conformity to target shape is improved, but the scan path length increases relative to the aperture size
Solution Approach 1:
The patent applies parameter changes by optimizing the scan path length relative to the collimator aperture size for each layer. Instead of using a fixed scan path, the system calculates the specific aperture shape and determines the optimal scan path parameters for each layer based on its collimator aperture dimensions. This dynamic parameter adjustment ensures that the scan path is appropriately scaled to each layer's aperture, maintaining dose distribution conformity while optimizing scan path efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach shortens the scan path length, reduces treatment time, and minimizes beam loss by focusing irradiation only on the collimator aperture area, enhancing beam utilization efficiency in both uniform scanning and conformal layer stacking irradiation techniques.
Implementation Method 1
a particle accelerator such as a synchrotron accelerator or a cyclotron accelerator
Implementation Method 2
transported to an irradiation nozzle by a beam transport system
Implementation Method 3
scanned by the scanning magnets so that the scanned beam fits the target shape
Implementation Method 4
the charged particle beam is enlarged by a scatterer
Data Source
AI summary
A charged particle beam reduces treatment time in the uniform scanning or in the conformal layer stacking irradiation. In the uniform scanning, an optimum charged particle beam scan path for uniformly irradiating a collimator aperture area is calculated. In the conformal layer stacking irradiation, an optimum charged particle beam scan path for uniformly irradiating a multi-leaf collimator aperture area of each layer for each of the layers obtained by partitioning the target volume is calculated. Alternatively, a minimum irradiation field size that covers the multi-leaf collimator aperture area of each layer is calculated, and a scan path corresponding to the irradiation field size, prestored in a memory of a particle therapy control apparatus, is selected. The charged particle beam scan path is optimally changed in the lateral directions in conformity with the collimator aperture area in the uniform scanning or in each layer in the conformal layer stacking irradiation.