Static Ion Beam Compensator for FLASH Radiotherapy
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Solution Overview
Problem
Traditional pencil beam scanning methods and rotating disk devices are not feasible for FLASH therapy due to the need for rapid energy changes and homogeneous dose distribution, which are not compatible with the short, high-dose rate pulses used in this therapy.
Innovation Solution
A passive compensating device with a disk-shaped structure and elongate elements of varying thickness and shape, designed using ray tracing and radiological path length concepts, allows for homogeneous dose distribution with a single energy level, enabling efficient treatment planning and manufacturing through 3D printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pencil beam scanning methods are used, then homogeneous dose distribution can be achieved, but treatment time becomes too long for FLASH therapy requirements
Solution Approach 1:
The compensator is pre-designed with specific thickness variations that encode the desired dose modulation pattern before treatment begins. By pre-calculating and fabricating the compensator geometry based on patient-specific anatomy and treatment goals, the system eliminates the need for real-time dynamic adjustments during FLASH therapy, enabling rapid single-energy delivery while maintaining homogeneous dose distribution.
Solution Approach 2:
The patent creates a physical copy of the dose distribution pattern through the compensator's thickness variations. Instead of dynamically modulating the beam, the compensator's static geometry copies the desired dose modulation pattern, allowing the beam to pass through and automatically produce the target dose distribution without real-time control interventions.
2Reliability
If a rotating disk device is used to spread Bragg peaks, then homogeneous dose coverage is achieved, but the device cannot operate at the required speed for FLASH therapy
Solution Approach 1:
Instead of moving the modulating elements (rotating disk) to achieve dose modulation, the patent inverts the approach by making the modulating elements stationary and varying their geometry (thickness) to achieve the same effect. This inversion eliminates the motion requirement entirely, allowing the device to operate at FLASH therapy speeds without mechanical rotation.
Solution Approach 2:
The patent changes the parameter of the compensator from dynamic rotation to static thickness variation. By encoding the dose modulation pattern in the compensator's thickness distribution rather than its motion, the system achieves homogeneous dose coverage without requiring high-speed rotation, making it compatible with FLASH therapy timing requirements.
3Adaptability or versatility
If multiple energy levels are used in pencil beam scanning, then flexible dose distribution is achieved, but the number of energy changes increases treatment time
Solution Approach 1:
The patent merges the functions of multiple energy levels into a single energy beam by using the compensator to modulate the dose distribution pattern. Instead of switching between different energy levels to achieve varying dose depths, the system combines all necessary dose modulation into a single pass through the compensator, eliminating repeated energy changes and reducing treatment time.
Solution Approach 2:
The compensator device performs multiple functions simultaneously: it acts as a range modulator, a dose distributor, and an energy filter all in one static component. This multi-functionality replaces the need for multiple separate energy levels and beam modulation steps, achieving flexible dose distribution with a single energy level delivery.
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 efficient and precise dose delivery in ion-based radiotherapy, particularly suitable for FLASH therapy, reducing the number of energy levels needed and allowing full target coverage with a single energy level, while accommodating complex dose distributions and uncertainties in patient geometry.
Implementation Method 1
providing an element of varying thickness made from a material that will attenuate the energy of the ions, thus shortening their path in dependence of the thickness of the compensator
Implementation Method 2
devices for spreading the Bragg peaks in the depth direction to achieve homogeneous dose coverage over the target volume
Data Source
Figure 1~2b
Figure 3~4
AI summary
A compensating device for use in ion-based radiotherapy may comprise a disk with a number of protrusions may be placed in a radiation beam to affect the ions in the beam in different ways to create an irradiation field from a broad beam. This is particularly useful in FLASH therapy because of the limited time available or modulating the beam. A method of designing such a compensating device is proposed, comprising the steps of obtaining characteristics of an actual treatment plan comprising at least one beam, determining at least one parameter characteristic of the desired energy modulation of the actual plan by performing a dose calculation of the initial plan and, based on the at least one parameter, computing a shape for each of the plurality of elongated elements to modulate the dose of the delivery beam to mimic the dose of the initial plan per beam.