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A broadband system for multifrequency static imaging in electrical impedance tomography.
1Divisió de Instrumentació i Bioenginyeria-DEE, Universitat Politècnica de Catalunya, Barcelona, Spain.
Summary
This study introduces a new electrical impedance tomography (EIT) system using broadband signals for improved tissue imaging. The developed EIT system enables static imaging by analyzing both real and imaginary impedance parts.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Electrical Engineering
Background:
- Static imaging in electrical impedance tomography (EIT) traditionally uses two fixed frequencies, limiting tissue differentiation.
- The selection of measurement frequencies is critical and application-specific for accurate tissue characterization.
Purpose of the Study:
- To develop an advanced EIT system capable of generating and applying broadband signals for enhanced static imaging.
- To improve the ability to distinguish between different tissue types by overcoming the limitations of fixed-frequency measurements.
Main Methods:
- A novel EIT system was designed to generate signals from 8-10(3) kHz and apply two simultaneously using a broadband current mirror.
- Careful design of the current injection multiplexer and patient interface board minimized output capacitance and feedthrough capacitance.
- Finite Element Method (FEM) and circuit simulations informed the design of driving and detection sections, accounting for skin and electrode effects.
Main Results:
- Simulations using FEM with tissue impedance data demonstrated the feasibility of static imaging.
- Preliminary measurements in a discrete phantom confirmed the capability for static imaging.
- The system allows for imaging of both the real and imaginary parts of tissue impedance.
Conclusions:
- The developed broadband EIT system successfully enables static imaging of tissue impedance.
- The system's design addresses critical challenges in capacitance and signal integrity for improved performance.
- This approach offers potential for enhanced differentiation of tissues in medical imaging applications.