Passive Electron Beam Intensity Modulator Using Island Blocks
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Solution Overview
Problem
Current methods for intensity modulation of electron beams in electron beam therapy are ineffective due to significant scattering in air, making it impractical to use X-ray multileaf collimators or proton beam scanning for electron beams, resulting in non-uniform dose distribution and increased exposure to healthy tissues.
Innovation Solution
The introduction of Island Blocks or Island Apertures in the electron beam collimator, which modulate the intensity of the electron beam by selectively blocking or allowing electrons to pass through, creating a controlled intensity pattern that can be optimized for specific treatments, allowing for passive radiotherapy intensity modulation (PRIME).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If X-ray multileaf collimators or proton beam scanning are used for electron beam intensity modulation, then intensity modulation capability is improved, but the method becomes ineffective due to significant scattering in air
Solution Approach 1:
The patent extracts the intensity modulation function from complex active systems (MLCs, scanning magnets) and implements it through a passive geometric structure (island blocks) that modulates the beam via scattering principles, eliminating the need for complex moving or scanning components in the electron beam path
Solution Approach 2:
The island blocks are simple, static, easily manufacturable components that can be quickly changed or replaced for different treatment plans, unlike expensive and complex MLCs or scanning systems, making the system adaptable and cost-effective
2Device complexity
If electron beams are used without intensity modulation, then device complexity is reduced, but dose distribution becomes non-uniform and exposure to healthy tissues increases
Solution Approach 1:
The patent converts the harmful effect of electron scattering in air into a beneficial mechanism by using controlled scattering from island blocks to achieve intensity modulation, turning what was previously a problem into the core functional principle of the system
Solution Approach 2:
The island blocks create localized modifications to the beam intensity at specific positions, allowing precise control of dose distribution in different regions of the treatment field while maintaining simplicity in the overall system design
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 method enables controlled intensity modulation of electron beams, achieving a nearly uniform dose distribution to the target tissue while minimizing exposure to healthy tissues, and can be easily integrated into existing clinical settings with minimal changes.
Implementation Method 1
electrons scattering from the non-uniform surface of the bolus or of the patient's body cause the dose in the PTV to be non-uniform; electron beams show significant scattering in the intervening air
Data Source
AI summary
Typically, electron beam radiation therapy aims at delivering a uniform dose to a target volume containing cancer cells. Electron sources typically impinge a spatially uniform flux across the beam onto the patient; however, irregular patient and bolus surfaces, the latter encountered in bolus electron conformal therapy (ECT), scatter electrons unevenly creating non-homogeneous dose distributions in the target. However, spatially-modulated beam intensities can restore target dose homogeneity, as well as enable utilization of other advanced ECT methods. Unfortunately, present methods, which have attempted to spatially-modulate beam intensities, have been either impractical or ineffective. Here, a novel, passive method has been developed to spatially-modulate electron beam intensities by taking advantage of multiple Coulomb scattering. The method utilizes Island Blocks or Island Apertures, strategically located in ‘transparent’ or ‘opaque’ substrates, respectively, which are placed in the beam's path. This method spatially-modulates electron flux across the beam with insignificant loss of electron beam energy. Thus, delivering a uniform, highly conformal dose distribution to the target volume is possible. Further, the method is inexpensive and can be easily incorporated into existing electron therapy machines.