Radiation Therapy Plan Optimization for MLC Edge Uncertainty

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Solution Overview

Problem

Current radiation therapy planning systems often fail to optimize therapy plans for individual patients, leading to suboptimal dose distributions due to uncertainties in radiation scatter and positioning inaccuracies at the edges of multi-leaf collimator apertures.

Innovation Solution

A system and method that incorporates an optimization function to account for uncertainties in radiation dose distribution at the edges of multi-leaf collimator apertures, using a therapy plan optimization unit to determine a sequence of apertures and fluence values that minimize these uncertainties while achieving desired therapeutic dose distributions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If radiation therapy plans are optimized using conventional algorithms, then the desired therapeutic radiation dose distribution can be achieved, but uncertainties in radiation scatter and positioning inaccuracies at the edges of multi-leaf collimator apertures remain unaccounted for

Engineering Contradiction:
Improvedose distribution accuracyVSAvoidedge positioning reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The optimization function incorporates additional parameters representing uncertainty in radiation scatter and positioning inaccuracies at aperture edges. By changing the optimization criteria to include these uncertainty parameters, the system adjusts the therapy plan to account for edge effects that were previously ignored, thereby improving both dose distribution accuracy and edge positioning reliability simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple therapy plans with different leaf position sequences are generated, then various dose distributions can be achieved, but it becomes difficult to determine which plan is most optimal for each patient

Engineering Contradiction:
Improvetherapy plan flexibilityVSAvoidoptimal plan identification
Core Design Contradiction:
Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The optimization function provides feedback by evaluating each therapy plan against the planning objectives and uncertainty parameters. This feedback mechanism automatically identifies the most optimal plan by selecting the one that best satisfies both the desired dose distribution and the uncertainty constraints, eliminating the need for manual evaluation of multiple plans.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If radiologists manually select therapy plans based on experience, then subjective judgment can be applied, but this decision process does not consistently lead to the most optimal therapy plan for each patient

Engineering Contradiction:
Improveplan selection simplicityVSAvoidtherapy plan optimization precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The optimization system performs self-service by automatically evaluating and selecting the optimal therapy plan based on quantitative criteria. The system independently processes the planning objectives, calculates dose distributions, assesses uncertainties, and determines the optimal plan without requiring radiologist intervention, thereby achieving both ease of operation and high precision consistently.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4069355B1System, method and computer program for determining a radiation therapy plan for a radiation therapy system
Publication Date: 2025.07.09 ELEKTA AB
  • EP4069355B1 patent drawingFigure 1
  • EP4069355B1 patent drawingFigure 2
  • EP4069355B1 patent drawingFigure 3

AI summary

The invention relates to a system for determining a radiation therapy plan for a radiation therapy system (100), comprising a multi-leaf collimator. The radiation therapy plan determination system (110) comprises a therapy system characteristics providing unit (111), wherein the characteristics comprise possible leaf positions and possible radiation fluence values, a planning objectives providing unit (112), wherein the planning objectives are indicative of a desired therapeutic radiation dose distribution, an optimization function providing unit (113), wherein the optimization function is indicative of a deviation of a radiation dose distribution from the planning objectives and of an uncertainty of the radiation dose distribution at edges of the possible apertures, and a therapy plan optimization unit (114) adapted to determine a sequence of possible apertures and possible radiation fluence values for which the optimization function is optimized. Thus, an optimal therapy plan can be provided for each individual patient.