Fan Beam Modulator for Ion Beams
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Solution Overview
Problem
Current proton therapy systems relying on time accumulation methods for intensity modulation in ion beam treatment face increased treatment times due to higher average intensities requiring longer exposure times, which can be impractical and costly to address with fast-acting shutters or pencil beam scanning systems.
Innovation Solution
A shutter system that controls instantaneous ion beam intensity by varying the longitudinal extension of latitudinally separate shutters in an area beam, which is then refocused to create a fan beam with uniform proton intensity, allowing continuous variation of instantaneous intensities without relying on time accumulation, combined with an energy modulator using ion attenuating wedges for independent control of intensity and energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If time accumulation methods are used for intensity modulation, then average intensity control is achieved, but treatment time increases
Solution Approach 1:
The patent applies dynamics by transitioning from static shutter positions to dynamic shutter movement. The shutter system continuously varies the longitudinal extension of shutters during beam delivery, enabling instantaneous intensity modulation rather than relying on time accumulation. This dynamic adjustment allows the system to achieve desired intensity profiles faster, directly resolving the contradiction between ease of intensity control and treatment time.
Solution Approach 2:
The patent changes the parameter of shutter extension position along the longitudinal axis to control intensity. By varying the longitudinal extension of shutters continuously during beam delivery, the system achieves instantaneous intensity modulation. This parameter change approach replaces time accumulation methods, allowing intensity control without increasing treatment time.
2Loss of time
If fast-acting shutters are designed to offset increased treatment times, then treatment time is reduced, but device complexity and cost increase
Solution Approach 1:
The patent segments the shutter system into multiple independently controllable shutter elements arranged latitudinally. Each shutter can be extended to different longitudinal distances independently, allowing fine-grained intensity control. This segmentation enables simpler, more manageable shutter components rather than requiring a single complex fast-acting shutter system, thus reducing overall device complexity while maintaining treatment time efficiency.
Solution Approach 2:
The patent introduces a longitudinal dimension to shutter control, extending shutters to different distances along the beam path rather than using only lateral positioning. This dimensional change allows continuous intensity modulation through the longitudinal extension variable, enabling treatment time reduction without requiring complex fast-acting mechanisms, as the modulation is achieved through position variation in the longitudinal dimension.
3Loss of time
If pencil beam scanning is used for intensity modulation, then treatment time is reduced, but device complexity and cost increase
Solution Approach 1:
The patent substitutes the mechanical pencil beam scanning system with a shutter-based intensity modulation system. Instead of mechanically scanning a pencil beam across the treatment area, the system uses shutter elements that block portions of a broader area beam. This substitution eliminates the need for complex scanning mechanisms while achieving similar treatment time reduction through instantaneous intensity control via shutter positioning.
4Ease of operation
If shutter intensity variations are obtained through duty cycle modulation, then intensity control is achieved, but treatment time increases
Solution Approach 1:
The patent implements continuity of useful action by maintaining continuous beam delivery while simultaneously varying shutter positions. Rather than using intermittent duty cycle modulation where the beam is on and off, the system continuously delivers protons while shutters dynamically adjust their longitudinal extension. This continuous action eliminates idle time and achieves intensity modulation without increasing total exposure time, directly resolving the contradiction between intensity control and treatment time.
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
Enables continuous and uniform control of ion beam intensity and energy within the beamlet area, reducing treatment time and complexity, while minimizing neutron production and allowing smooth continuous modulation during gantry rotation.
Implementation Method 1
The partially occluded area beam is then refocused to a fan beam
Implementation Method 2
a set of latitudinally adjacent ion-blocking shutters controllably extended to different longitudinal distances
Data Source
AI summary
An intensity modulator for controlling the intensity of ions, such as protons, controllably block a portion of sub-areas of an area beam to control the average intensity within that sub-area. A fan beam is then created by a focusing process that reforms the area beam while blurring intensity variations in each sub-area to a corresponding beamlet in the fan beam of uniform intensity.