Breathing Signal Phase Histogram for Radiation Therapy Latency

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Solution Overview

Problem

Current radiation therapy techniques face challenges in accurately compensating for breathing motion due to latency in target localization and machine component control, and periodic imaging of internal targets increases radiation dose to the patient.

Innovation Solution

A processor-based system processes breathing signals to determine non-periodicity and predict breathing patterns, allowing for real-time adjustment of radiation delivery and reducing the need for periodic imaging by using a camera to monitor patient breathing and generate a signal-phase histogram to identify deviations from normal patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If periodic imaging of internal target region is used to verify position, then measurement precision is improved, but radiation dose to patient increases

Engineering Contradiction:
Improveposition verification accuracyVSAvoidradiation dose
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces continuous periodic imaging with event-triggered imaging based on breathing non-periodicity detection. The system monitors breathing patterns continuously and only triggers imaging when deviations from periodic breathing are detected, thus reducing unnecessary radiation exposure while maintaining position verification accuracy when needed.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system uses the patient's own breathing signal as a trigger mechanism. By analyzing the breathing pattern's periodicity, the system automatically determines when imaging is necessary, eliminating the need for predetermined periodic imaging schedules and reducing redundant radiation exposure.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If current target localization methods are used, then position determination is achieved, but latency in localization and control reduces accuracy

Engineering Contradiction:
Improvetarget position determination accuracyVSAvoidlocalization and control latency
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of breathing signal periodicity continuously during treatment. By detecting non-periodicity in advance, the system can trigger imaging and adjust radiation delivery proactively, compensating for the inherent latency in imaging and mechanical control systems.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback loop where breathing signals are continuously monitored, periodicity is analyzed, and deviations trigger corrective actions (imaging or radiation adjustment). This real-time feedback mechanism ensures that position determination remains accurate despite system latencies by continuously adapting to actual breathing patterns.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2693940B1Prediction of breathing signal using signal-phase histogram
Publication Date: 2022.05.25 VARIAN MEDICAL SYSTEMS INC
  • EP2693940B1 patent drawingFigure 1
  • EP2693940B1 patent drawingFigure 2
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AI summary

A method of processing breathing signals of a subject includes obtaining breathing signals of a subject, obtaining a signal-phase histogram using the breathing signals, wherein the signal-phase histogram comprises a plurality of data points, each of the data points having at least a phase value and a signal value, determining a reference value using at least some of the plurality of data points from the signal-phase histogram, determining whether a difference between the reference value and a signal value that is associated with a current respiratory cycle exceeds a threshold, and generating an output when the difference exceeds the threshold. A method of predicting breathing signal is also provided.