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ABSTRACT: This paper illustrates how breast tissue composition, modeled by different mixtures of adipose and glandular tissues, affects the accuracy of microwave breast imaging for different sizes of malignant lesions. To study this, the scattered field for different tissue composition and various tumour sizes was calculated using a Frequency Dependent Finite Difference Time Domain ((FD)2TD) approach. Images are generated from the scattered field, together with Genetic Algorithm (GA) optimization methods. The scattered field calculations show that it is strongly dependent not only on the dielectric properties and size of the breast tissue, but also on the specific tissue composition. The tumour response is the difference between scattered fields of a specific tissue composition with and without the tumour. The response of a 1.5cm tumour was found to be 6.7 times larger when it is embedded within homogeneously uniform fatty tissue than when embedded within homogeneously uniform fibro-glandular tissue. For a tumour inside a heterogeneously dense breast consisting of a mix of fi bro-glandular and fatty tissues, this value is 5.2. The consequences of the biological heterogeneity on the forward and inverse simulation, and on the accuracy of images obtained by microwave imaging using the proposed method were studied. The robustness of our approach to variations in the breast phantom was shown. This technique returned highly accurate results with millimetre resolution. The most rigorous test to date demonstrated that we are able to accurately reconstruct an image of the dielectric properties of a 7.5mm lesion embedded in fibro-glandular tissue at a depth of 6cm in a heterogeneous numerical breast phantom.
Canadian Journal of Electrical and Computer Engineering 02/2010; · 0.24 Impact Factor
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ABSTRACT: The recent information about breast tissue properties presented in [1] was used to design a new inverse scattering method for the application of breast imaging. The proposed method uses the combination of real and binary GAs which reduces the computational cost. The binary GA was used for the discrete search space that only finds the type of the tissue and real GA was used to find the water content percentage which covers a domain of real variables. The method was tested on a simulated example and showed promising results. Future studies will be performed to verify this method with experimental data.
Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 08/2008
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ABSTRACT: This paper addresses the nonlinear tomographic image reconstruction problem with particular emphasis on developing efficient numerical algorithms for early breast cancer detection using parallel algorithms to enhance both the speed and quality of the recovered images. Our goal is to illustrate an effective method of microwave imaging for early stage breast cancer detection, using parallel finite-difference time domain method (PFDTD) and parallel genetic algorithms (PGAs) optimization, by using message passing interface (MPI) library.
Antennas and Propagation Society International Symposium, 2007 IEEE; 07/2007
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ABSTRACT: This paper addresses a two-dimensional inverse scattering method with a combination of tomography and radar methods for breast cancer detection. In order to rapidly construct high resolution images displaying the location, size, permittivity and conductivity of malignant tumors inside the body, the collected reflection from the scattered fields present in the scan area is segmented and their associated dielectric property maps are calculated. The dielectric profiles are obtained by using a technique that combines frequency domain finite difference time domain (FD)<sup>2</sup>TD analysis with genetic algorithm (GA) optimization. The applications of the proposed method can vary from medical imaging to nondestructive testing of materials and structures. The proposed technique yielded promising results when applied to simulated data
Engineering in Medicine and Biology Society, 2006. EMBS '06. 28th Annual International Conference of the IEEE; 10/2006
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ABSTRACT: This paper addresses the versatility of the frequency domain finite difference time domain (FD)<sup>2</sup>TD method in dealing with dispersive biological media. (FD)<sup>2</sup>TD is an extended version of the conventional FDTD that can handle dispersive materials more accurately. The conventional FDTD has been previously used for the modeling of biological tissues at a single frequency using constant material parameters. The frequency dependence of biological materials can be efficiently described in the time domain using standard Debye or Lorentz models. These models can be expressed in different orders. The higher order models can represent any arbitrary dispersive medium at the expense of computational cost and complexity. In order to maintain the simplicity of the method and to reduce computational cost, the first order Debye model is employed
Antennas and Propagation Society International Symposium 2006, IEEE; 08/2006
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ABSTRACT: In this paper we have analyzed microstrip fractal patch antennas using 3D finite difference time domain (FDTD) method and compared the results with experimental and numerical ones obtained by commercial software Ansoft Ensemble. The application of fractal geometry to conventional antenna structure optimizes the shape of the antenna in order to increase its electrical length. Microstrip fractal patch antennas are capable of achieving wide bandwidth, multiband operation, and reduced antenna size for lower resonance frequency range.
Antenna Technology: Small Antennas and Novel Metamaterials, 2005. IWAT 2005. IEEE International Workshop on; 04/2005
