Ridge Filter Point Symmetric Design for Particle Beam Therapy
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Solution Overview
Problem
In particle beam therapy, the scanning irradiation method requires minute spot arrangement due to sharp Bragg peaks, leading to prolonged treatment times and high beam energy requirements, with existing ridge filters facing challenges in processing and maintaining uniform dose distribution, especially for large targets and small spot sizes.
Innovation Solution
A ridge filter design with point symmetric and bilaterally asymmetric structures arranged in the iterative direction, featuring equal thicknesses in the depth direction and no sharp portions, which disperses the beam energy and spreads the Bragg peak width without increasing the size of the beam delivery system, allowing for uniform dose distribution across large targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanning irradiation method is used with minute spot arrangement to achieve uniform dose distribution, then the dose distribution uniformity is improved, but the treatment time is prolonged and the dose rate decreases
Solution Approach 1:
The ridge filter is divided into multiple structures arranged in the iterative direction, with each structure having specific thickness patterns that segment the beam attenuation function. This segmentation allows different portions of the beam to be attenuated by different amounts, spreading the Bragg peak width and enabling fewer spots to achieve uniform dose distribution, thereby reducing treatment time while maintaining dose uniformity
Solution Approach 2:
The patent changes the physical parameters of the ridge filter structures, specifically the thicknesses in the iterative direction of uppermost and lowermost stream surfaces. By optimizing these thickness parameters and arranging structures with point symmetric and bilaterally asymmetric shapes, the Bragg peak is spread out, allowing coarser spot arrangement and faster treatment while maintaining uniform dose distribution
2Productivity
If the Bragg peak width is spread out by increasing the ridge filter height, then the dose rate is improved and treatment time is reduced, but the processing difficulty increases and the ridge filter becomes more prone to damage
Solution Approach 1:
The patent employs both point symmetric and bilaterally asymmetric structures in the ridge filter. The bilaterally asymmetric shape allows the Bragg peak to be spread effectively without requiring excessive filter height. This asymmetric design achieves the desired peak spreading with moderate filter dimensions, making the filter easier to process and less prone to damage while maintaining high dose rate
Solution Approach 2:
The patent inverts the conventional approach by using point symmetric structures where the center of gravity serves as the symmetric point, rather than using traditional asymmetric mountain-like structures. This inversion allows the ridge filter to achieve effective Bragg peak spreading with reduced height and without sharp portions, improving manufacturability and structural integrity while maintaining high dose rate
3Manufacturing precision
If the iterative interval of the ridge filter is minutely set to match spot size, then the dose distribution uniformity is improved, but the device complexity and manufacturing precision requirements increase
Solution Approach 1:
The ridge filter structures are designed with point symmetric and bilaterally asymmetric shapes that serve multiple functions simultaneously: they spread the Bragg peak width, maintain dose distribution uniformity, and work effectively with various spot sizes. This multi-functionality allows the same filter design to be used across different treatment scenarios without requiring minute adjustments to the iterative interval, reducing device complexity while maintaining precision
Solution Approach 2:
By optimizing the thickness parameters of the ridge filter structures and using symmetric/asymmetric arrangements, the patent achieves effective Bragg peak spreading with coarser iterative intervals. This parameter optimization reduces the stringency of manufacturing precision requirements and simplifies the overall device complexity while maintaining uniform dose distribution
4Productivity
If a large amount of beam energy is prepared to cover all spots, then the dose rate is improved, but the time and effort required for quality assurance increases
Solution Approach 1:
The ridge filter segments the beam energy distribution by using multiple structures with different thicknesses in the iterative direction. This segmentation creates a spread-out Bragg peak that covers the target volume more efficiently, allowing the system to use optimized beam energy levels rather than preparing excessive energy for all possible spots. This reduces the complexity and time required for quality assurance while maintaining high dose rate
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 design reduces treatment time, minimizes beam energy requirements, and enhances processing efficiency, ensuring accurate and robust dose distribution without damaging the ridge filter, while maintaining a compact beam delivery system.
Implementation Method 1
a first structure 301 and a second structure 302 which attenuate energy of a particle beam passing therethrough
Data Source
AI summary
A structure configuring a ridge filter has line symmetry about a line vertical to a depth direction passing the center of the structure. A small structure obtained in such a way that the structure is divided by this line has a bilaterally asymmetric shape about a center line in an iterative direction, and has a point symmetric shape about an intersection between the center line in the iterative direction and the center line in the depth direction. Thicknesses in the iterative direction of an uppermost stream surface and a lowermost stream surface in the depth direction are equal to each other. The structure is configured so that a thick portion in the iterative direction of the uppermost stream surface and the lowermost stream surface is not present in the depth direction.