TTFields Electrode Impedance Tomography for Accurate Field Planning
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Solution Overview
Problem
Existing methods for estimating the field intensity of Tumor Treating Fields (TTFields) treatment rely on conductivity values from scientific literature, leading to inaccurate estimates of power density in tumors, as they do not account for the actual electrical characteristics of individual subjects.
Innovation Solution
Measuring actual impedances between electrode elements on the subject's body to generate a precise model of the electrical characteristics, allowing for accurate calculation of field intensity and power density without relying on literature-based conductivity assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If numeric simulation techniques with literature-based conductivity values are used to estimate field intensity, then the treatment planning process is simplified and can be performed without subject-specific measurements, but the accuracy of field intensity and power density estimates deteriorates because actual tissue electrical characteristics are not accounted for
Solution Approach 1:
The system performs preliminary impedance measurements on the subject's body before treatment planning. These measurements are taken in advance to characterize the actual electrical properties of the subject's tissues, which are then used to improve the accuracy of field intensity calculations during treatment planning.
Solution Approach 2:
The system uses measured impedance values from the subject's body as feedback to adjust and refine the field intensity calculations. The actual electrical characteristics obtained from measurements feed back into the simulation model to correct assumptions about tissue conductivity, thereby improving measurement precision.
2Measurement precision
If subject-specific impedance measurements are performed to improve field intensity accuracy, then measurement precision improves, but the complexity of the treatment planning process increases due to additional measurement and modeling steps
Solution Approach 1:
The system uses a multi-functional approach where the same electrode array serves dual purposes: both delivering the tumor treating fields and performing impedance measurements. This eliminates the need for separate measurement devices and integrates multiple functions into a single system, reducing overall complexity despite the enhanced measurement capabilities.
Solution Approach 2:
The electrode arrays themselves perform the measurement function without requiring external specialized equipment. The system uses its own operational components to gather the necessary electrical characteristic data, making the complex measurement process self-contained and reducing external dependencies.
3Productivity
If literature-based conductivity values are assumed for all tissue types, then the modeling process is faster and requires fewer measurements, but the reliability of power density determination deteriorates due to inter-subject variability in tissue electrical properties
Solution Approach 1:
Instead of using uniform conductivity values for all tissues, the system determines local electrical characteristics by measuring impedance at specific locations on the subject's body. Each measurement location provides information about the local tissue properties, allowing the model to reflect actual variations in electrical characteristics across different regions of the individual subject.
Solution Approach 2:
The system changes the conductivity parameters in the simulation model based on actual measurements from the subject. Rather than using fixed literature values, the electrical parameters are adjusted to match the measured impedance characteristics of the specific subject, thereby improving reliability while maintaining reasonable modeling speed.
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
Provides improved accuracy in determining the field intensity and power density delivered to tumors by using actual impedance measurements, eliminating the need for cumbersome finite element simulations and enhancing treatment planning.
Implementation Method 1
Measuring actual impedances between electrode elements on the subject's body to generate a precise model of the electrical characteristics
Implementation Method 2
applying low intensity, intermediate frequency (e.g., 100-500 kHz), alternating electric fields
Data Source
Figure 1A~1D
Figure 2
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AI summary
Treatment of a target region using alternating electric fields (e.g., TTFields) may be planned by determining, based on a plurality of impedance measurements obtained during a first window of time, a first impedance at each of a plurality of voxels that correspond to the target region. Then, based on the first impedances, a plan for treating the target region with alternating electric fields is generated. Subsequently, an electric field may be induced in the target region based on the plan. In some embodiments, a baseline MRI of the target region is obtained, and contemporaneous baseline impedances are registered to the MRI. In these embodiments, the plan for treating the target region is further based on a comparison between the first impedances and the baseline impedances.