Particle Beam Scanning Apparatus for Tumor Irradiation
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Solution Overview
Problem
Conventional particle beam therapy systems face challenges in enlarging beam spots for tumor irradiation without reducing maximum beam energy and increasing the penumbra of dose distribution, leading to unnecessary dose irradiation on normal tissues.
Innovation Solution
A particle beam irradiation apparatus with a scanning apparatus that includes two scanning means to two-dimensionally scan and control charged particle beams, allowing for pseudo-enlargement of beam spots without reducing maximum beam energy, using a first scanning means for high-speed scanning and a second scanning means for adjusting beam positions to achieve a desired dose distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a scattering material such as lead is inserted into the beam path to enlarge the beam spot size, then the beam spot size is increased to cover larger tumor regions, but the maximum range of the charged particle beam is reduced by the thickness of the scattering material, leading to energy loss
Solution Approach 1:
The patent divides the beam spot enlargement function into two independent scanning means: a first scanning means for high-speed scanning to create a pseudo-enlarged spot, and a second scanning means for adjusting beam positions to achieve the desired dose distribution. This segmentation eliminates the need for scattering materials that cause energy loss while maintaining the ability to cover large tumor regions.
Solution Approach 2:
The patent replaces the mechanical approach of inserting scattering materials (physical enlargement method) with an electromagnetic scanning system that uses deflection magnetic fields or electric fields to achieve beam spot enlargement through coordinated scanning motions. This substitution preserves beam energy while achieving the same enlargement effect.
2Productivity
If the beam spot size is enlarged through insertion of scattering material, then fewer beam spots are needed to cover the target region, but the penumbra of the dose distribution increases, causing unnecessary dose irradiation on normal tissues
Solution Approach 1:
The patent employs dynamic scanning control where the first scanning means operates at high speed to create the pseudo-enlarged spot, while the second scanning means dynamically adjusts beam positions to achieve the desired dose distribution. This dynamic approach maintains a small penumbra while covering large areas, preventing unnecessary dose to normal tissues.
Solution Approach 2:
The patent changes the operational parameters of the scanning system by using two independent scanning means with different functions: one for high-speed pseudo-enlargement and another for precise position adjustment. This parameter differentiation allows maintaining a sharp dose distribution edge (small penumbra) while achieving large coverage area.
3Area of moving object
If scattering material is inserted to enlarge beam spots for carbon beams, then the beam spot size is increased, but a further thicker scattering material is required compared to proton beams, resulting in larger beam energy loss
Solution Approach 1:
The patent replaces the scattering material approach with an electromagnetic scanning system that uses deflection magnetic fields or electric fields to achieve beam spot enlargement. This substitution is particularly beneficial for carbon beams, which require thick scattering materials and suffer significant energy loss, by preserving beam energy while achieving the same enlargement effect through coordinated scanning motions.
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 eliminates unnecessary beam energy loss, maintains a small penumbra, and allows for precise, high-accuracy three-dimensional dose distribution, reducing unnecessary dose to normal tissues and enabling deeper tumor irradiation with the same maximum beam energy.
Implementation Method 1
control is performed with a scanning electromagnet in such a way that a charged particle beam spot is scanned over the cross section of an irradiation target situated on a plane perpendicular to the irradiation direction of the charged particle beam spot
Implementation Method 2
The beam spot enlargement through insertion of a scattering material is to utilize increase in the angular variance of a beam caused by scattering
Data Source
AI summary
In order to obtain a particle beam irradiation apparatus that enlarges the dose distribution of beam spots while suppressing a decrease of the maximum available range of a charged particle beam, the particle beam irradiation apparatus includes a particle beam acceleration means; particle beam transport means; scanning apparatus that includes first scanning means and second scanning means, and two-dimensionally scans the beam; and irradiation control means that controls the scanning apparatus so as to irradiate the beam onto a target region including a plurality of small regions. The irradiation control means controls the first scanning means so as to scan the beam over a small region serving as an irradiation subject among the plurality of the small regions, and controls the second scanning means so as to change the small region serving as the irradiation subject to be a different small region among the plurality of the small regions.