Radiation Treatment Plan Optimization for Time Efficiency

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Solution Overview

Problem

Current radiation therapy treatment plans are inefficient, leading to longer treatment times due to complex transitions between treatment fields, requiring manual adjustments and prolonged beam-off times, which can expose healthy tissues to unnecessary radiation and increase patient discomfort.

Innovation Solution

An optimized spatial point sequence is determined to minimize total treatment time by interleaving and intermixing treatment fields, with an optimization algorithm that considers beam-on and beam-off times, clinical protocols, and hardware constraints, while penalizing excessive monitor unit (MU) counts to ensure collision-free and time-efficient trajectories.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If complex treatment fields (IMRT, VMAT, 3D conformal) are used to deliver radiation precisely to the target while avoiding healthy tissue, then treatment precision and dose distribution are improved, but treatment time increases due to long transitions between consecutive fields

Engineering Contradiction:
Improveradiation delivery precisionVSAvoidtotal treatment time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The treatment plan is segmented into multiple treatment fields (IMRT, VMAT, 3D conformal) with specific spatial points and trajectories. Each field is defined by control points including source-to-surface distance, source-to-axis distance, gantry angle, couch angle, and MLC positions. This segmentation allows independent optimization of each field's precision while enabling efficient sequencing to minimize total transition time.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies dynamic optimization to determine the optimal sequence and trajectory of treatment fields. The system dynamically adjusts the order of fields and their corresponding spatial points to minimize total treatment time while maintaining precision. This includes optimizing the transition paths between fields and determining when to switch between different treatment modalities based on real-time constraints and objectives.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If longer travel distances for treatment axes are used to access different spatial points for treatment fields, then treatment coverage and precision are improved, but transition time between fields increases

Engineering Contradiction:
Improvespatial point accuracyVSAvoidtransition speed
Core Design Contradiction:
Manufacturing precisionVSSpeed

Solution Approach 1:

The system performs preliminary optimization to pre-determine the optimal sequence of treatment fields and their corresponding spatial points. By calculating the best trajectory path in advance, the system minimizes unnecessary travel distances and positions fields to reduce transition time. The optimization algorithm considers all constraints (clearance margins, mechanical limits) beforehand to create an efficient treatment sequence.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The optimization process incorporates feedback mechanisms that continuously monitor treatment parameters and adjust the sequence accordingly. The system evaluates transition times, spatial point requirements, and field constraints to dynamically refine the treatment trajectory. This feedback loop ensures that the optimal sequence is maintained while adapting to any variations in treatment requirements or machine capabilities.

Inventive Principle:
Principle #23Feedback

3Reliability

If manual adjustment and human supervision are used during transitions between treatment fields, then treatment safety and precision are improved, but treatment time increases

Engineering Contradiction:
Improvetreatment safetyVSAvoidbeam-off time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs self-service optimization by automatically determining the optimal treatment sequence and trajectory without requiring manual intervention during execution. The optimization algorithm independently calculates the best field sequence, transition paths, and timing, eliminating the need for real-time manual adjustments. This automated self-optimization maintains safety through built-in constraint checking while significantly reducing beam-off time.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical adjustment with computational optimization algorithms. Instead of relying on human operators to manually adjust fields and monitor transitions, the system uses computer-based optimization to automatically determine the optimal treatment sequence. This substitution of mechanical/manual processes with computational methods maintains precision and safety while eliminating time-consuming manual interventions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If excessive monitor unit (MU) counts are used to ensure adequate radiation dose delivery, then treatment completeness is improved, but treatment time increases

Engineering Contradiction:
Improvedose delivery completenessVSAvoidbeam-on time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system optimizes treatment parameters including monitor unit (MU) counts, dose rates, and field sequencing to achieve the required dose delivery in minimal time. The optimization algorithm adjusts MU counts dynamically based on the specific treatment requirements, spatial points, and transition constraints. By changing these parameters optimally, the system ensures complete dose delivery without excessive MU accumulation that would increase treatment time.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3515555B1Optimization of radiation treatment plans for optimal treatment time in external-beam radiation treatments
Publication Date: 2020.11.25 VARIAN MEDICAL SYST INT AG
  • EP3515555B1 patent drawingFigure 1
  • EP3515555B1 patent drawingFigure 2
  • EP3515555B1 patent drawingFigure 3

AI summary

An optimized radiation treatment plan may be developed in which the total monitor unit (MU) count is taken into account, A planner may specify a maximum treatment time. An optimization algorithm may convert the specified maximum treatment time to a maximum total MU count, which is then used as a constraint in the optimization process. A cost function for the optimization algorithm may include a term that penalizes any violation of the upper constraint for the MU count.