Movable Layer Primary Collimator for Compact Radiotherapy Heads
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Solution Overview
Problem
Current linear accelerators for medical applications require multiple filters and collimators that increase mechanical load and complexity, as they need to be tailored for specific beam energy options, leading to inefficiencies and increased mass due to scattered radiation shielding.
Innovation Solution
A primary collimator with multiple independently movable layers, each containing apertures with different filters, allowing for customizable beam shaping and energy modification within the same structure, reducing the need for a separate filter carousel and shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple filters and collimators are added to achieve specific beam energy options, then beam customization capability is improved, but device complexity and mass increase
Solution Approach 1:
The primary collimator is divided into multiple independently movable layers, each containing different filter options. This segmentation allows selective positioning of filter layers to achieve different beam energy configurations without requiring a complete separate filter assembly, thereby reducing overall device complexity while maintaining customization capability.
Solution Approach 2:
The primary collimator structure is designed to serve dual functions: both collimation and filtration. By integrating filter layers within the collimator assembly, the device achieves multiple beam customization capabilities without adding separate dedicated filter components, thus improving adaptability while controlling device complexity.
2Adaptability or versatility
If filters are placed on a rotating carousel, then beam energy options are improved, but weight and mechanical load increase
Solution Approach 1:
The filter layers are merged with the primary collimator structure rather than being placed on a separate rotating carousel. This integration eliminates the need for a heavy carousel mechanism and its associated shielding, significantly reducing the weight of the moving filter assembly while maintaining the capability to provide multiple beam energy options through selective layer positioning.
3Object-affected harmful factors
If shielding is added around filters to prevent scattered radiation, then radiation safety is improved, but mass and mechanical load increase
Solution Approach 1:
The shielding function is merged with the primary collimator structure itself. The collimator layers and their support structure provide inherent radiation shielding as they perform collimation, eliminating the need for additional separate shielding components. This integration maintains radiation safety by containing scattered radiation while avoiding the mass penalty of redundant shielding.
4Adaptability or versatility
If a separate filter carousel is used, then beam modification capability is improved, but the depth and size of radiation head increase
Solution Approach 1:
The filter modification capability is merged into the primary collimator assembly, eliminating the need for a separate downstream filter carousel. This integration consolidates the radiation head structure, reducing its overall depth and size while maintaining full beam modification capability through the selective positioning of collimator layers with different filter properties.
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 enables easier switching between various beam configurations, reduces the overall weight and depth of the radiation head, and improves mechanical accuracy by integrating beam modification elements within the collimator, eliminating the need for additional shielding and a filter carousel.
Implementation Method 1
a primary collimator for delimiting the thus-produced beam to a first extent... the primary collimator consists of a plurality of layers arranged transversely to the beam, each layer having a plurality of apertures
Implementation Method 2
The filters that are available for use in such apparatus usually include sections of solid material (such as Nickel) which have an x-ray absorption spectrum corresponding to an energy which needs to be removed from the x-ray beam
Data Source
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Figure 2
Figure 3~6
AI summary
The primary collimator for a radiotherapy apparatus can be made up of several layers, each comprising several apertures, and each layer being moveable so as to select a specific aperture to build up the primary collimator shape. In this way, the shape of the primary collimator can be tailored and/or the beam filters incorporated into the primary collimator assembly. This saves space in the radiation head whilst also allowing filters to be easily interchanged.