Ion Beam Spot Size Control for Proton Therapy Trade-offs
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Solution Overview
Problem
Current proton therapy systems face challenges in achieving a balance between treatment speed and accuracy, with existing methods either being fast but less precise or accurate but slower, and are susceptible to patient movement leading to uneven dose placement.
Innovation Solution
A radiotherapy system that uses multiple beam spot sizes to vary the lateral and axial extent of ion beams, allowing for precise control and adaptation to different treatment areas, using focusing magnets, quadrupole magnets, and mechanical collimators to steer and shape the beams according to a radiation plan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the proton beam is expanded to subtend the entire tumor with spread in range, then treatment speed is improved, but manufacturing precision (dosimetric accuracy) deteriorates
Solution Approach 1:
The patent segments the tumor treatment into multiple smaller beam spots of varying sizes rather than using a single large expanded beam. The system delivers treatment by scanning multiple pencil beams across the tumor volume, with each beam independently controlled for size and position. This segmentation allows the system to achieve both speed (by treating multiple regions simultaneously) and precision (by using smaller, more controllable beam spots)
Solution Approach 2:
The patent implements dynamic beam size control where the lateral width of the ion beam is varied as a function of control signals during the treatment process. The beam controller dynamically adjusts beam parameters based on the radiation plan, allowing the system to adapt beam size to different treatment requirements in real-time, thus optimizing both speed and precision
2Manufacturing precision
If the proton beam remains narrowly collimated in a pencil beam, then manufacturing precision (dosimetric accuracy) is improved, but productivity (treatment speed) deteriorates
Solution Approach 1:
The patent divides the treatment into multiple pencil beam exposures that scan across the tumor volume. By segmenting the treatment this way, the system maintains the precision benefits of narrow beams while improving speed through parallel treatment of multiple tumor regions via multiple beams operating simultaneously
Solution Approach 2:
The patent transitions from a single-beam approach to a multi-beam scanning approach, adding the dimension of spatial distribution. Multiple pencil beams are scanned across different portions of the tumor, effectively treating the tumor in parallel across multiple spatial dimensions, thus improving treatment speed without sacrificing the precision of individual beam spots
3Manufacturing precision
If a specially constructed range correction compensator is used, then manufacturing precision (dosimetric accuracy) is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the complex range correction compensator from the system. Instead of using a specially constructed compensator to achieve precise dose distribution, the system achieves the same precision through direct control of beam parameters (lateral width, range, and positioning) without requiring additional complex hardware components
Solution Approach 2:
The patent replaces the mechanical range correction compensator with electronic/control-based beam parameter adjustment. The beam controller dynamically adjusts beam width, energy, and position through control signals, substituting the need for physical compensators with a more flexible and simpler control system
4Manufacturing precision
If small spot sizes are used in successive exposures, then manufacturing precision (dosimetric accuracy) is improved, but reliability deteriorates due to patient movement causing cold spots
Solution Approach 1:
The patent implements dynamic beam size adjustment where the lateral width is varied based on treatment requirements. The system can expand beam spots when treating larger, more homogeneous regions to improve reliability and reduce the impact of patient movement, while maintaining small spot sizes for precise delineation where needed
Solution Approach 2:
The patent changes beam parameters (lateral width, axial extent, energy) dynamically during treatment based on the radiation plan and patient position. By adjusting these parameters in real-time, the system can compensate for patient movement and maintain reliable dose placement while preserving precision where required
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 approach enables a flexible trade-off between treatment speed and accuracy, reducing the risk of 'cold spots' due to patient movement and optimizing energy use by controlling beam width without blocking, thus improving treatment uniformity and efficiency.
Implementation Method 1
using focusing magnets, quadrupole magnets, and mechanical collimators to steer and shape the beams
Implementation Method 2
protons may be controlled to stop within the tissue, reducing or eliminating exit dose through healthy tissue on the far side of the tumor
Implementation Method 3
the dose deposited by a proton beam is not uniform along the entrance path of the beam, but rises substantially to a 'Bragg peak' near a point where the proton beam stops within the tissue
Implementation Method 4
using focusing magnets, quadrupole magnets, and mechanical collimators to steer and shape the beams
Data Source
AI summary
An ion radiation therapy machine provides a steerable beam for treating a tumor within the patient where the exposure spot of the beam is controlled in width and/or length to effect a flexible trade-off between treatment speed, accuracy, and uniformity.