Spot-wise Beam Current Control in Particle Therapy

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Solution Overview

Problem

Current particle therapy treatment plans face challenges in delivering high dose rates over short times, such as in FLASH treatment, while minimizing variability and errors in beam output current, which affects the therapeutic efficacy and tissue sparing.

Innovation Solution

A closed-loop feedback spot-wise beam current control system and method are implemented, which includes a beam monitor, a closed-loop feedback control module, and a beam source. This system adjusts the source beam current based on treatment plan parameters and real-time output beam current measurements to minimize errors and optimize MU rates for each spot.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional particle therapy treatment plans use constant beam current for each layer, then the treatment delivery is simple and stable, but the MU rate cannot be optimized for high MU spots, limiting the dose rate and treatment efficiency

Engineering Contradiction:

ImproveMU rateVSAvoidbeam current control system

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the beam current control into spot-wise independent control, where each spot can have its own optimized MU rate and beam current settings, rather than using a constant beam current for the entire layer. This allows high MU spots to receive higher dose rates while low MU spots receive appropriate lower rates, maximizing overall treatment efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic beam current adjustment during treatment delivery, where the beam current is varied in real-time based on the specific spot being treated and its required MU rate. This dynamic control enables optimization of dose rate for each spot while maintaining overall treatment plan integrity.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If high dose rate radiation is delivered in short time periods (FLASH treatment), then normal tissue is spared from radiation-induced toxicity, but the variability and errors in beam output current increase, affecting therapeutic efficacy

Engineering Contradiction:

Improvenormal tissue toxicityVSAvoidbeam output current accuracy

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent implements a closed-loop feedback control system that continuously monitors the actual beam output current and compares it to the desired current. The system then adjusts the beam current in real-time to compensate for variations and maintain accurate dose delivery, even during high dose rate FLASH treatments.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical/current-based beam current control with an optical measurement and control system. Beam output is measured using ionization chambers and optical detectors, and the control system uses electronic feedback rather than purely mechanical adjustment, improving precision and reducing variability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If spot-wise MU rates are specified to maximize MU rates for high MU spots, then treatment efficiency is improved, but the variability and errors in magnitude of beam output current increase, requiring more complex control

Engineering Contradiction:

Improvetreatment efficiencyVSAvoidbeam output current precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The closed-loop feedback system continuously measures actual beam output current at each spot and compares it to the target current derived from the treatment plan. The system dynamically adjusts the beam current to minimize errors and maintain precision despite varying MU rate requirements across different spots.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes beam current parameters (magnitude, timing, duration) based on the specific requirements of each spot. The system adjusts multiple parameters simultaneously to achieve optimal MU rates for high MU spots while maintaining precision through real-time feedback control.

Inventive Principle:

Principle #35Parameter changes

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

The closed-loop feedback control system enhances the precision and accuracy of beam delivery, allowing for higher MU rates and improved therapeutic outcomes while reducing normal tissue toxicity, thus effectively addressing the limitations of conventional treatment plans.

Implementation Method 1

The beam current and profile monitor 145 can include an array of detectors and a sampling processor configured to sample charge values between ionization chamber plates of the array of ionization detectors to determine accumulation, beam current, and beam profile parameters

Methodology Applied

Scientific EffectIonization: Ionisation

Data Source

PatentUS12208286B2Particle therapy closed-loop feedback spot-wise beam current control systems and methods

Publication Date: 2025.01.28 VARIAN MEDICAL SYST PARTICLE THERAPY GMBH & CO KG

AI summary

Techniques for closed-loop feedback beam control in particle therapy delivery system can include receiving treatment plan beam parameters, receiving a determined output beam current of a present spot, generating an adjusted source beam current set point based on the treatment plan beam parameters and the determined output beam current of the present spot, and adjusting an output beam current of the present spot based on the adjusted source beam current.