Dual-Material Collimator Leaves for IMRT
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Solution Overview
Problem
Current radiation therapy collimators are heavy, costly, and inefficient, particularly in intensity modulated radiation therapy (IMRT), where irradiation time is prolonged due to complex dose distribution requirements, and they fail to effectively minimize radiation exposure to healthy tissues.
Innovation Solution
A collimator design featuring pairs of leaves with high-attenuating penumbra-trimming portions made of high atomic number metals like tungsten or osmium and low-attenuating support portions made of lighter metals like steel or aluminum, optimized for rapid intensity modulation and reduced weight, allowing for faster and more precise beam shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional collimator leaves made of high-attenuation materials (e.g., tungsten) are used throughout the entire leaf structure, then radiation attenuation capability is improved, but weight and manufacturing cost increase significantly
Solution Approach 1:
The collimator leaf is divided into two distinct regions with different material properties: a penumbra-trimming portion made of high-attenuation material (tungsten, osmium, or iridium) and a support portion made of low-attenuation material (aluminum or steel). This local differentiation allows the high-attenuation material to be concentrated only where it is most needed for radiation control, while the majority of the leaf structure uses lighter materials, thereby reducing overall weight without compromising radiation attenuation capability.
Solution Approach 2:
The collimator leaf employs a composite structure combining two different metal materials with contrasting properties. The high-attenuation metal (tungsten, osmium, or iridium) provides superior radiation blocking capability in the penumbra-trimming region, while the low-attenuation metal (aluminum or steel) provides structural support with minimal weight. This composite approach optimizes the balance between radiation attenuation and weight reduction.
2Object-affected harmful factors
If conventional collimator leaves made of high-attenuation materials are used throughout the entire leaf structure, then radiation attenuation capability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The collimator leaf is divided into two distinct regions with different material properties: a penumbra-trimming portion made of high-attenuation material (tungsten, osmium, or iridium) and a support portion made of low-attenuation material (aluminum or steel). This local differentiation allows the high-attenuation material to be concentrated only where it is most needed for radiation control, while the majority of the leaf structure uses lighter materials, thereby reducing overall weight without compromising radiation attenuation capability.
Solution Approach 2:
The collimator leaf employs a composite structure combining two different metal materials with contrasting properties. The high-attenuation metal (tungsten, osmium, or iridium) provides superior radiation blocking capability in the penumbra-trimming region, while the low-attenuation metal (aluminum or steel) provides structural support with minimal weight. This composite approach optimizes the balance between radiation attenuation and weight reduction.
3Manufacturing precision
If dynamic multileaf collimation is used to achieve intensity modulation, then dose distribution precision is improved, but irradiation time increases significantly
Solution Approach 1:
The collimator leaves are designed to be dynamically adjustable during radiation therapy treatment, allowing real-time modification of the beam shape and intensity distribution. The leaves can move independently to create complex dose patterns while maintaining precision, and the dynamic capability enables faster treatment delivery compared to static collimation methods.
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
The design significantly reduces irradiation time, minimizes dose to healthy tissues, and lowers the overall weight and cost of the collimator, enabling efficient and precise radiation therapy with reduced edge scatter and improved patient throughput.
Implementation Method 1
The penumbra-trimming portion constitutes the leaf portion in connection with the leaf end facing the opposite collimator leaf of the leaf pair. The support portion is then the major leaf portion facing away from the opposite leaf of the leaf pair. A provided radiation beam, such as a photon, electron or light ion beam, preferably a narrow scanned pencil beam, will substantially only incident on the penumbra-trimming leaf portion. As a consequence, the material of this inner portion has a high linear radiation attenuation capability radiation
Implementation Method 2
the material of this inner portion has a high linear radiation attenuation capability radiation, which is larger than the corresponding linear attenuation capability of the support portion
Data Source
AI summary
A collimator (1) primarily adapted for usage in a narrow scanned pencil beam radiation therapy system (100) includes adjacent pairs (5) of collimator leaves (10, 20). An inner portion (12) of a collimator leaf (10) facing the opposite leaf (20) of a pair (5) is made of a first material having high linear radiation attenuation. The remaining, major portion (14) of the leaf (10) is made of a second material having a comparatively low density, weight and radiation attenuation. The collimator (1) provides effective penumbra trimming of a radiation beam (60), while simultaneously protecting healthy tissue around a tumor in an irradiated patient (80) from the radiation. The new design results in a significantly more compact, lighter and less expensive collimator (1) as compared to traditional collimators.