Viable Three-Dimensional Medical Microwave Tomography: Theory and Numerical Experiments

Area of Science:

• Medical Imaging
• Computational Electromagnetics
• Biomedical Engineering

Background:

• Three-dimensional (3D) microwave tomography promises enhanced accuracy over 2D techniques by minimizing approximations.
• Computational efficiency is a major challenge for practical 3D microwave imaging due to increased problem complexity.

Purpose of the Study:

• To present and evaluate two novel 3D image reconstruction methods for microwave tomography.
• To investigate strategies for improving computational efficiency in 3D microwave imaging.

Main Methods:

• Developed two 3D image reconstruction algorithms using scalar and vector field modeling.
• Employed Finite Element (FE) and Finite-Difference Time-Domain (FDTD) methods for electromagnetic field simulation in 3D.
• Extended 2D reconstruction techniques (dual-mesh, iterative block solver, adjoint Jacobian) to 3D and explored speed improvements using initial field estimates and Alternating-Direction Implicit (ADI) FDTD.

Main Results:

• Successfully reconstructed the position, size, and electrical properties of targets using simulated data.
• Demonstrated significant reductions in computation time with the adjoint formulation and FDTD using initial field estimates.
• Confirmed the critical role of cross-plane measurements for accurate 3D profile reconstruction.

Conclusions:

• The proposed 3D microwave tomography methods are effective in reconstructing target properties.
• Computational efficiency for 3D imaging is significantly improved through advanced FDTD techniques and adjoint formulations.
• Cross-plane measurements are essential for achieving high-fidelity 3D reconstructions in microwave tomography.