Arm-Shape Collimator for Charged Particle Beam Shaping
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Solution Overview
Problem
Current particle therapy treatments using scanning irradiation methods face challenges in achieving sharpness of dose distribution at the edge of the irradiation target, leading to potential damage to normal tissues outside the target area, due to limitations in shaping the collimator leaves to match complex tumor shapes.
Innovation Solution
A charged particle irradiation apparatus with a collimator apparatus in the irradiation nozzle, featuring arm-shape collimators with movable leaves that can rotate and move independently on a plane perpendicular to the beam path, allowing precise blocking of the charged particle beam to prevent irradiation outside the target edge, thereby enhancing dose concentration on the tumor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multi-leaf collimators are used to match beam shape to tumor contour, then dose distribution can be improved, but drive control becomes more complex proportionally to the number of leaves
Solution Approach 1:
The collimator is divided into multiple independent leaves that can be controlled separately. Each leaf can be independently positioned to create complex tumor-shaped fields, allowing precise dose distribution control while maintaining manageable individual component complexity
Solution Approach 2:
The collimator leaves are made dynamically controllable through drive mechanisms that allow real-time adjustment of leaf positions. This dynamic capability enables adaptation to various tumor shapes and sizes without requiring physically different collimator configurations
2Manufacturing precision
If dynamic trimming collimators are used to block beam at irradiation target edge, then sharpness of dose distribution is improved, but ability to change shape to match complex tumor edges is insufficient
Solution Approach 1:
The collimator consists of multiple independent leaves rather than a single trimmer, enabling the creation of complex polygonal shapes that can match irregular tumor contours while maintaining sharp dose distribution edges through precise leaf positioning
Solution Approach 2:
Different regions of the collimator (different leaves) can be positioned independently to create locally optimized beam blocks that match the specific geometry of tumor edges in different areas, providing both sharpness and shape adaptability
3Device complexity
If charged particle beam is scanned spot by spot without collimator, then particle therapy treatment is simplified, but sharpness of dose distribution at irradiation target edge deteriorates
Solution Approach 1:
The collimator is positioned upstream in the beam path to pre-shape the charged particle beam before it reaches the scanning magnets. This preliminary shaping action ensures that the beam maintains its sharp edges throughout the scanning process, enabling spot-by-spot irradiation with high dose distribution sharpness
Data Source
AI summary
The invention provides a charged particle irradiation apparatus including: a collimator apparatus provided in an irradiation nozzle that emits a charged particle beam to an irradiation target; and a collimator control unit that controls the collimator apparatus. The collimator apparatus includes a collimator mechanism having one or more arm-shape collimators extending from a base part and a drive mechanism that moves the collimator mechanism on a plane perpendicular to a traveling direction of a charged particle beam. The arm-shape collimator includes one or more movable leaves that rotate independently of each other on the perpendicular plane. By moving the collimator mechanism and/or rotating the movable leaves so that the arm-shape collimators are arranged along a shape of an edge of an irradiation target on the perpendicular plane, the collimator control unit causes the arm-shape collimators to block a charged particle beam that would otherwise irradiate outside of the edge of the irradiation target.