Fast Microwave Tomography Algorithm for Breast Cancer Imaging
Despite the need for an alternative screening technique, microwave tomography has not yet been introduced as a screening modality in regular health care, and is still subject to research. The main obstacles are imperfect hardware systems and inefficient imaging algorithms. The immense computational costs for the image reconstruction algorithm present a crucial challenge. 2D imaging algorithms are proposed to reduce the amount of hardware resources required and the imaging time. Although 2D microwave tomography algorithms are computationally less expensive, 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: the forward problem and the inverse problem. The first part of this thesis focuses on a new fast forward solver, the 2D discrete dipole approximation (DDA), which is formulated and modeled. The effect of frequency, sampling number, target size, and contrast on the accuracy of the solver are studied. Additionally, the 2D DDA time efficiency and computation time as a single forward solver are investigated. The second part of this thesis focuses on the inverse problem. This portion of the algorithm is based on a log-magnitude and phase transformation optimization problem and is formulated as the Gauss-Newton iterative algorithm. The synthetic data from a finite-element-based solver (COMSOL Multiphysics) and the experimental data acquired from the breast imaging system at Chalmers University of Technology are used to evaluate the DDA-based image reconstruction algorithm. The investigations of modeling and computational complexity show that the 2D DDA is a fast and accurate forward solver that can be embedded in tomography algorithms to produce images in seconds. The successful development and implementation in this thesis of 2D tomographic breast imaging with acceptable accuracy and high computational cost efficiency has provided significant savings in time and in-use memory and is a dramatic improvement over previous implementations.
discrete dipole approximation
Chalmers, Elektroteknik, Signalbehandling och medicinsk teknik, Biomedicinsk elektromagnetik
Expansion of the nodal-adjoint method for simple and efficient computation of the 2d tomographic imaging jacobian matrix
Sensors,; Vol. 21(2021)p. 1-16
Inledande text i tidskrift
Application of two-dimensional discrete dipole approximation in simulating electric field of a microwave breast imaging system
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology,; Vol. 3(2019)p. 80-87
Artikel i vetenskaplig tidskrift
A discrete dipole approximation solver based on the COCG-FFT algorithm and its application to microwave breast imaging
International Journal of Antennas and Propagation,; Vol. 2019(2019)
Artikel i vetenskaplig tidskrift
Samar Hosseinzadegan, Andreas Fhager, Mikael Persson, Shireen Geimer, and Paul Meaney, Discrete Dipole Approximation-Based Microwave Tomography for Fast Breast Cancer Imaging.
The key to increasing the chance of survival in breast cancer is regular monitoring. For breast cancer imaging applications, the devices should be designed to be portable, cost effective, sensitive to various tissue types, user-friendly, harmless and comfortable for patients. Microwave technology has a great potential to meet these requirements, but it is still being developed, and has not yet been fully translated to the clinical setting. The benefit of a non-ionizing technique that does not require breast compression is particularly appealing for patient safety and comfort. Developing such imaging devices will require developing a fast and accurate electromagnetic solver.
The thesis focuses on the microwave tomography technique for fast breast cancer imaging. It is devoted to investigating the computational aspects and to addressing the heavy computational burden of microwave tomographic reconstruction algorithms. Two-dimensional (2D) images of breasts are obtained in a few seconds. The work is validated with both simulated and measured data. These 2D results are an important piece of the puzzle for simplifying and reducing system size, cost, and speed towards eventual deployment in under-resourced environments which are currently not able to establish conventional breast screening programs.
Hälsa och teknik
Elektroteknik och elektronik
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4916
Chalmers tekniska högskola
Opponent: Prof. Ari Sihvola, Aalto University, Finland