Tumor Tracking Correlation via Breathing Phase Volumetric Reconstruction
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Solution Overview
Problem
Current surrogate monitoring systems for tumor motion during radiotherapy lack stability and statistical confidence due to limited breathing cycles and inability to accurately represent internal tumor position, especially in techniques using external markers and kV planar imaging.
Innovation Solution
A method involving acquiring and reconstructing volumetric images from projection images with similar breathing phases to establish a reliable correlation between surrogate signals and tumor positions, allowing for confident and real-time tracking and gating during treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If surrogate monitoring systems use external markers and kV planar imaging to track tumor position, then the system can be easily repeated and implemented, but the correlation between marker position and internal tumor position becomes unstable over time and lacks statistical confidence
Solution Approach 1:
The patent segments the correlation establishment process into multiple independent measurements taken at different time points during treatment. Instead of relying on a single correlation determination, the system performs repeated measurements and combines them statistically, allowing the correlation to be updated and verified throughout the treatment course, thereby maintaining stability over time.
Solution Approach 2:
The system implements continuous feedback by periodically re-measuring the correlation between external markers and internal tumor position using kV planar imaging throughout the treatment course. This feedback mechanism allows detection of correlation drift and enables recalcibration, ensuring the surrogate monitoring remains accurate despite changes in patient anatomy or positioning over time.
2Productivity
If surrogate monitoring systems use limited breathing cycles for correlation determination, then the measurement process is quick and efficient, but the statistical confidence in the correlation result is low
Solution Approach 1:
The patent applies continuity by accumulating correlation data across multiple treatment sessions and breathing cycles. Rather than relying on a single set of measurements, the system continuously gathers data points from repeated kV planar imaging acquisitions throughout treatment, combining them to build a robust statistical foundation that maintains high confidence while allowing for efficient individual measurements.
3Loss of information
If 4D CT is used to establish correlation between external markers and internal tumor position, then soft tissue target and critical structures can be visualized, but the system cannot be easily repeated and requires extensive scanning time
Solution Approach 1:
The patent extracts the essential correlation information from the complex 4D CT process by using only the necessary imaging components. Instead of performing full 4D CT scans for routine correlation checks, the system uses targeted kV planar imaging to measure marker positions and correlates them with pre-established 4D CT data, obtaining the needed correlation information without the time penalty of repeated volumetric scanning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a stable and confident correlation between surrogate signals and tumor positions, enabling accurate and timely tracking and gating, improving the reliability of tumor location determination and radiation delivery.
Implementation Method 1
acquiring a plurality of projection images of a patient
Implementation Method 2
reconstructing a plurality of volumetric images of the patient from the projection images
Data Source
AI summary
The present invention therefore provides a method for the analysis of radiographic images, comprising the steps of acquiring a plurality of projection images of a patient, acquiring a surrogate signal indicative of the location of a target structure in the patient, reconstructing a plurality of volumetric images of the patient from the projection images, each volumetric image being reconstructed from projection images having a like breathing phase, identifying the position of the target structure such as a tumor in each volumetric image, associating a surrogate signal with each of the projection images, and determining a relationship between the surrogate signal and the position of the target structure. Multiple projection images having a like breathing phase can be grouped for reconstruction, to provide sufficient numbers for reconstruction. The analysis of the multiple values of the surrogate associated with each breathing phase can be used to determine the mean surrogate value and its variation. Multiple values of the surrogate signal associated with the same nominal breathing phase can be used to determine a mean value of the surrogate signal for the target position associated with that phase and a variation of the value of the surrogate signal for the target position associated with that phase. The breathing phase of specific projection images can be obtained by analysis of one or more features in the images, such as the method we described in U.S. Pat. No. 7,356,112, or otherwise.