Variable Thickness Absorber for Rapid Ion Beam Energy Switching
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Solution Overview
Problem
Current charged particle therapy systems face challenges in quickly changing energy levels, achieving high ion beam current at desired energy levels, accessing shallow ranges without secondary devices, and are costly due to complex beam transport and facility requirements, which are time and cost prohibitive.
Innovation Solution
An energy selection system with a variable thickness absorber housed within the nozzle of the charged particle therapy system, capable of adjusting its thickness along the beam axis to change ion beam energy, and includes a gantry and absorber that can move relative to the ion beam, or a closed fluid dynamic system with a liquid absorber to adjust energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ion beam energy is changed at the ion accelerator, then the desired energy level is achieved, but the treatment time increases and system complexity increases
Solution Approach 1:
The energy selection function is extracted from the ion accelerator and relocated to a downstream position near the patient. This allows the accelerator to operate at fixed high energy while a separate, simpler energy selection system handles energy modulation, thereby reducing overall system complexity and enabling faster energy switching.
Solution Approach 2:
An intermediary energy selection system is introduced between the ion accelerator and the patient. This intermediary system uses a variable thickness absorber to modulate beam energy without requiring the accelerator itself to change energy levels, thus decoupling the complex accelerator system from the energy selection requirement.
2Speed
If beam transport magnets are adjusted to account for energy changes, then the correct beam path is maintained, but the switching time increases
Solution Approach 1:
The energy selection is performed downstream after the beam has been accelerated and transported. This preliminary positioning of the energy selection function allows the beam transport magnets to operate at fixed settings, eliminating the need for time-consuming magnet adjustments during energy changes.
3Adaptability or versatility
If a range modulator wheel is used to vary ion beam energy, then energy adjustment is achieved, but the device size becomes prohibitively large for pencil-beam scanning
Solution Approach 1:
The mechanical range modulator wheel is replaced with a variable thickness absorber system that can be positioned downstream. This substitution eliminates the need for a large rotating wheel mechanism while achieving the same energy modulation function, making the system compact and suitable for pencil-beam scanning.
Solution Approach 2:
Instead of using a large wheel that modulates energy in one dimension (rotational position), the invention uses a variable thickness absorber that achieves energy modulation through dimensional variation in absorber thickness. This allows energy selection without requiring large mechanical structures.
4Ease of manufacture
If conventional radiation therapy facilities are used, then the facility footprint is small, but energy selection and beam transport complexity increases cost
Solution Approach 1:
The complex energy selection and beam transport systems are extracted and consolidated into a compact downstream configuration near the patient. This extraction allows the facility to maintain a small footprint while reducing the complexity of the overall system by eliminating the need for extensive beam transport infrastructure.
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 rapid and precise energy adjustment of ion beams, reducing treatment time, system complexity, and cost, while maintaining high beam current and minimizing radiation exposure, allowing for more compact and efficient therapy systems.
Implementation Method 1
a variable thickness absorber that is configured to be housed within a nozzle of the charged particle therapy system and operable to adjust its thickness along a beam axis of the charged particle therapy system in order to change the energy of an ion beam passing through the variable thickness absorber
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A variable thickness energy selection system for use in a charged particle therapy system is arranged within the nozzle housing downstream of monitoring systems, such as a dose monitor and spot position monitor. This positions the energy selection system proximal to the patient. The thickness of an absorber within the energy selection system can be varied quickly without requiring the ion beam to be turned off between energy selections, thereby allowing for rapid control of the energy selection of the ion beam. The absorber may include one or more high density solid absorbers, or a high-density liquid absorber contained in a closed fluid dynamic system that includes an enclosure positioned within the beam path and a reservoir positioned outside of the beam path.