Radiotherapy Setup Error Quantification Using Encapsulation Metrics
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Solution Overview
Problem
Existing radiotherapy systems lack simple, quantifiable metrics to accurately assess changes in patient anatomy between planning and treatment sessions, leading to potential misalignment of Clinical Volumes (CV) and Planning Envelope Volumes (PEV), which can result in inadequate radiation delivery or exposure to sensitive organs.
Innovation Solution
A method to determine an encapsulation metric by defining Clinical Volumes and Planning Envelope Volumes, calculating the shortest distance of representative points, and using a signed distance transform to quantify the extent of CV encapsulation within PEV, allowing for real-time monitoring and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual comparison of planning and treatment images is performed manually, then user judgment can be applied, but quantifiable metrics and automation are lacking
Solution Approach 1:
The patent replaces manual visual comparison with an automated computational system that calculates an encapsulation metric. The system uses image processing algorithms to automatically determine the degree of overlap between CV and PEV, substituting human judgment with quantitative computational analysis.
Solution Approach 2:
The patent introduces an encapsulation metric as an intermediary quantitative measure between the planning and treatment images. This metric serves as a mediator that translates complex spatial relationships into a single quantifiable value that can be automatically assessed and tracked.
2Reliability
If margins are applied to create PTV and PRV to account for position variation, then robustness to anatomical changes is improved, but the complexity of treatment planning increases
Solution Approach 1:
The patent implements a feedback mechanism that monitors the actual position of CV relative to PEV during treatment and provides quantitative information about alignment. This feedback allows clinicians to adjust patient positioning or treatment parameters based on measured deviations, improving reliability while managing complexity through automated measurement.
3Productivity
If automated position correction is implemented, then treatment efficiency is improved, but the ability to detect and quantify alignment errors before correction is reduced
Solution Approach 1:
The patent performs preliminary quantification of alignment errors by calculating the encapsulation metric before any position correction is applied. This preliminary assessment preserves information about the original misalignment, allowing clinicians to understand the magnitude and direction of errors before automated correction systems adjust patient positioning.
Data Source
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AI summary
A method and system for determining changes between a planning image and a treatment image of a subject is described. The method comprising the steps of: defining one of more clinical volumes on the planning image of a subject and defining a planning envelope volume around the clinical volume for the planning image; acquiring a treatment image from the subject for a location corresponding to the location of the planning image; wherein the treatment image will have the same planning envelope volume as the planning image; determining the location of the one or more clinical volumes on the treatment image relative to the planning envelope volume; determining an encapsulation metric for one or more of the clinical volumes defining the extent of encapsulation of the clinical volume on the treatment image within the planning envelope volume on the treatment image.