Radiation Therapy Planning for Overlapping Target and Organ at Risk

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Solution Overview

Problem

In radiation therapy, treatment planning faces challenges when different structures with conflicting treatment objectives overlap, making it difficult to satisfy both objectives simultaneously, especially when a target structure and an organ at risk overlap, as the dose requirements for these structures are often incompatible.

Innovation Solution

A computer-implemented method and system that detect conflicts between treatment objectives by defining a margin around one of the structures, redefining regions of interest, and generating modified treatment objectives for non-overlapping and overlapping regions to resolve the conflicts, allowing for a more effective dose distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a single treatment plan is used for overlapping structures, then the treatment process is simple, but it is impossible to satisfy both treatment objectives simultaneously

Engineering Contradiction:
Improvetreatment planning simplicityVSAvoidtreatment objective satisfaction
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent divides the overlapping structure into multiple substructures, each representing a different tissue type or anatomical region. This segmentation allows separate treatment objectives to be assigned to each substructure, enabling the treatment plan to address conflicting dose requirements by treating each segment independently rather than as a single homogeneous structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different treatment objectives and dose constraints to different regions within the overlapping structure. By assigning tissue-specific properties and treatment parameters to each substructure, the system enables localized optimization where different parts of the same structure receive appropriate doses based on their specific radiation sensitivity and treatment requirements.

Inventive Principle:
Principle #3Local quality

2Reliability

If separate treatment plans are created for each structure, then both treatment objectives can be satisfied, but the treatment planning complexity increases

Engineering Contradiction:
Improvetreatment objective satisfactionVSAvoidtreatment planning complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a unified treatment plan framework that simultaneously handles multiple structures and their conflicting objectives. The system integrates dose calculation, optimization, and evaluation into a single multi-objective optimization process, allowing the treatment planning system to function universally for both simple and complex overlapping scenarios without requiring separate planning workflows.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extends the treatment planning from traditional single-structure optimization to multi-structure optimization by adding the dimension of multiple simultaneous objectives. This is achieved by formulating a cost function that incorporates dose metrics for multiple structures, transforming the problem from one-dimensional (single structure) to multi-dimensional (multiple structures with conflicting requirements) optimization.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If the dose to the target structure is increased to meet treatment objectives, then the target receives adequate radiation, but the dose to the overlapping organ at risk exceeds safe limits

Engineering Contradiction:
Improvetarget dose adequacyVSAvoidorgan at risk damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the overlapping structure into target tissue and organ-at-risk tissue, allowing separate dose constraints to be applied to each segment. This enables the optimization algorithm to deliver adequate dose to the target while simultaneously protecting the organ at risk by treating them as distinct entities with different dose requirements within the same spatial region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent modifies treatment parameters such as beam angles, intensities, and modulation patterns to achieve dose distribution that satisfies both target coverage and organ-at-risk constraints. By adjusting these parameters in the optimization process, the system finds solutions that deliver therapeutic doses to targets while reducing exposure to sensitive overlapping structures.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3524322B1Optimizing radiation dose to overlapping structures
Publication Date: 2020.11.18 VARIAN MEDICAL SYST INT AG
  • EP3524322B1 patent drawingFigure 1
  • EP3524322B1 patent drawingFigure 2
  • EP3524322B1 patent drawingFigure 3

AI summary

In radiation therapy, treatment objectives applicable to different identified structures in a patient's body (e.g., a target structure and an organ at risk (OAR)) may conflict due to overlap between the structures. Automated systems and methods can detect and resolve such conflicts. For example, a set of modified regions that do not overlap with each other can be defined at 708, and a modified treatment objective 708 for each modified region can be determined based on the original treatment objectives. The modified regions and modified treatment objectives can be used in treatment planning processes.