IMRT Geometric Complexity Metric for Plan Feasibility

Solution Overview

Problem

The complexity of intensity modulated radiation therapy (IMRT) planning leads to significant computing time and potential failure in generating a realizable treatment plan, due to the large number of variables and geometric complexities involving target volumes and organs at risk, often requiring multiple optimization attempts and clinician intervention.

Innovation Solution

A radiation therapy planning device and method that computes an achievability estimate for IMRT geometry by comparing the number of available beamlets intersecting the target volume and organs at risk, using a geometric complexity metric, to provide guidance on the likelihood of plan achievability before initiating optimization, thereby reducing wasted computing time and providing semi-automated parameter selection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional IMRT optimization is performed with multiple beam pulses and MLC configurations, then dosage distribution precision is improved, but computing time and complexity increase significantly

Engineering Contradiction:

Improvedosage distribution precisionVSAvoidplanning complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing a geometric complexity assessment before initiating the full IMRT optimization process. The system calculates a geometric complexity metric based on the spatial relationships between target volumes, organs at risk, and beam geometries, and uses this metric to predict optimization success. This preliminary evaluation allows clinicians to adjust planning parameters before committing to computationally intensive optimization, thereby reducing wasted computing time and complexity while maintaining dosage precision.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the number of beamlets and optimization variables is increased, then dosage modulation capability is improved, but optimization convergence and realiability decrease

Engineering Contradiction:

Improvedosage modulation capabilityVSAvoidoptimization convergence

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements feedback by using the geometric complexity metric to provide information about the likelihood of successful optimization convergence. The system calculates this metric from the IMRT geometry and compares it against thresholds or historical data to predict whether the optimization will converge successfully. This feedback mechanism allows clinicians to adjust beam configurations, target definitions, or organ-at-risk constraints before optimization to improve the chances of successful convergence while maintaining dosage modulation capability.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If multiple optimization attempts are performed to achieve a realizable plan, then plan quality is improved, but time consumption and clinician effort increase

Engineering Contradiction:

Improveplan qualityVSAvoidcomputing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing a geometric complexity assessment before initiating the full IMRT optimization process. The system calculates a geometric complexity metric based on the spatial relationships between target volumes, organs at risk, and beam geometries, and uses this metric to predict optimization success. This preliminary evaluation allows clinicians to adjust planning parameters before committing to computationally intensive optimization, thereby reducing wasted computing time and complexity while maintaining dosage precision.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10881875B2Pre-optimization method for quick prediction of achievability of clinical goals in intensity modulated radiation therapy

Publication Date: 2021.01.05 ELEKTA AB

AI summary

An achievability estimate is computed for an intensity modulated radiation therapy (IMRT) geometry (32) including a target volume, an organ at risk (OAR), and at least one radiation beam. Namely, a geometric complexity (GC) metric is computed for the IMRT geometry that compares a number NT of beamlets of the at least one radiation beam available in the IMRT geometry for irradiating the target volume and a number n of these beamlets that also pass through the OAR. A GC metric ratio is computed of the GC metric for the IMRT geometry and the GC metric for a reference IMRT geometry for which an IMRT plan is achievable. If the clinician is satisfied with this estimate then optimization (38) of an IMRT plan for the IMRT geometry (32) is performed. Alternatively, a reference IMRT geometry is selected by comparing the GC metric with GC metrics of past IMRT plans.