A Discrete Dipole Approximation Forward Solver for Microwave Breast Imaging
One important challenge is high computational demands of microwave tomography algorithms. 3D tomography algorithms require multiple hours and a large amount of hardware resources to produce images. 3D imaging algorithms are usually implemented and tested for simulations setup and barely used in clinical settings. 2D microwave tomography algorithms are computationally less expensive compared to 3D algorithms. Few imaging groups have been successful in integrating the acquired 3D data into the 2D tomography algorithms for clinical applications.
The microwave tomography algorithms include two main computation problems; forward and inverse. The forward problem has to be solved multiple times and the resulting computational cost is the time limiting step in microwave tomography algorithms, and this thesis is devoted to addressing it.
In this thesis, the two-dimensional forward problem is modelled and formulated. In particular, the two-dimensional discrete dipole approximation (DDA) is proposed as a new forward solver for microwave tomography. The accuracy of the 2D DDA with respect to sampling number, size, and contrast of target are investigated. Moreover, the 2D DDA time efficiency and computation time are studied.
The forward solver computation times for direct, iterative, and iterative combined with fast Fourier transformation (FFT) solvers are calculated. The observations imply that the 2D DDA is an accurate, reliable, and rapid forward solver, and using the Krylov subspace methods combined with the FFT accelerate the computation time significantly.
Chalmers, Elektroteknik, Signalbehandling och medicinsk teknik
Application of Two-Dimensional Discrete Dipole Approximation in Simulating Electric Field of a Microwave Breast Imaging System, S Hosseinzadegan, A Fhager, M Persson, P Meaney IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology
A Discrete Dipole Approximation Solver Based on the COCG-FFT Algorithm and its Application to Microwave Breast Imaging, Samar Hosseinzadegan, Andreas Fhager, Mikael Persson, and Paul Meaney
Room HA2, Hörsalsvägen 4
Opponent: Associate Professor Robin Augustine, Uppsala University