Three dimensional finite difference time domain simulations on harmonic motion microwave doppler imaging method using realistic tissue models

Download

index.pdf

Date

2019

Author

Tatar, Fikret

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

146
views

103
downloads

Imaging of electromagnetic and elastic properties of the breast tissue can be used to identify cancerous regions in the dense fibro glandular breast tissue at the early stage. Numerical simulations are useful in predicting the performance of the imaging method. In Harmonic Motion Microwave Doppler Imaging Method (HMMDI), tissue is vibrated locally, microwave signals illuminate the tissue and the back scattered Doppler signal component is used to form images. In this thesis, forward problem of HMMDI method is solved with various numerical tissue models using the 3-D (Three dimensional) Finite Difference Time Domain (FDTD) method. In the forward problem solution, mechanical and electromagnetic problems are examined separately. In the mechanical problem, the acoustic radiation force of amplitude modulated focused ultrasound waves is used to produce local vibrations inside the tissue. According to mechanical simulation results, displacement values in tumor region are smaller compared to the breast tissue region as expected and increasing frequency decreases the displacement values. In electromagnetic problem, transmitter antenna sends a monochromatic signal during focused ultrasound excitation, and a receiver antenna is used to receive the amplitude and phase modulated reflected signal. In the forward problem calculations, computation speed is an important issue since a large number of iterations (>1000) is needed in the FDTD solution. In this thesis, the forward problem is solved with parallel programming in Matlab. 19 times acceleration is achieved when GPU is employed compared to CPU case. Using the developed simulation tools, the received HMMDI signal is analyzed using three types of breast tissue models. Firstly, tumor inside a homogenous breast tissue problem is solved. The received Doppler signal amplitude increases in the tumor region in this case. In the second type, a tumor is located inside the fibro glandular tissue. Tumor and fibro glandular tissue have the same electrical properties but their mechanical properties are different. The received Doppler amplitude decreases in tumor region, since tumor is stiffer. In the third case, a tumor in realistic breast tissue model is tested. Simulations are run with and without the tumor in the breast tissue. The results show that the Doppler signal levels change in the tumor region by 0.5 to 2 dB, compared to the case without the tumor. The difference in the Doppler signal amplitude increase with decreasing mechanical vibration frequency. In conclusion, the tumor is detectable in all cases.

Subject Keywords

Microwave imaging in medicine., Keywords: Microwave Imaging, Finite Difference Time Domain Method, Parallel Programming, Breast Cancer.

URI

http://etd.lib.metu.edu.tr/upload/12624458/index.pdf
https://hdl.handle.net/11511/44564

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Harmonic motion microwave doppler imaging method Top, Can Barış; Gençer, Nevzat Güneri; Department of Electrical and Electronics Engineering (2013) Conventional method for breast tumor detection, mammography, has a number of drawbacks such as X-ray exposure, patient discomfort and loss of reliability especially for dense breast tissue. Therefore, it is a hot research topic to develop new alternative non-invasive, reliable, safe and patient friendly breast imaging methods. In this thesis, we propose a novel hybrid mechanical and electromagnetic imaging method to identify cancerous regions particularly inside dense glandular breast tissue at the early st...
A Microwave Imaging Model for Biomedical Applications ÖZGÜN, ÖZLEM; Kuzuoğlu, Mustafa (2017-07-14) A microwave imaging model is presented for detection of breast cancer tissues by combining the finite element method and the transformation electromagnetics approach. An inverse scattering problem is formulated based on genetic optimization algorithm, and its expensive cost function evaluations are accelerated by using the transformation electromagnetics approach, which allows using a uniform or rectangular mesh even when irregular geometries are present inside the domain. Simulation results are demonstrate...
Received Signal in Harmonic Motion Microwave Doppler Imaging as a Function of Tumor Position in a 3D Scheme IRGIN, Umit; TOP, Can Baris; TAFRESHI, Azadeh Kamali; Gençer, Nevzat Güneri (2017-02-08) Harmonic Motion Microwave Doppler Imaging method, which was proposed as an alternative method for breast tumor detection, is a combination of microwave radar and focused ultrasound techniques yielding data depending on electrical and mechanical properties of the tissue. In this study, Harmonic Motion Microwave Doppler Imaging data from a small tumor inside homogeneous fat is analyzed as a function of tumor location on three orthogonal planes using Finite Difference Time Domain simulations. The results show ...
Microwave Sensing of Acoustically Induced Local Harmonic Motion: Experimental and Simulation Studies on Breast Tumor Detection top, Can Baris; TAFRESHI, Azadeh Kamali; Gençer, Nevzat Güneri (2016-11-01) Sensing acoustically induced local harmonic motion using a microwave transceiver system may provide useful information for detecting nonpalpable tumors in dense breast tissue. For this purpose, we propose the harmonic motion microwave Doppler imaging method, in which the first harmonic of the phase modulated signal due to local harmonic motion is sensed. This signal is related to the dielectric, elastic, and acoustic properties of the vibrating region. The purpose of this paper is twofold: 1) to demonstrate...
Coordinate transformation aided finite element method for contour detection of breast tumors in microwave imaging ÖZGÜN, ÖZLEM; Kuzuoğlu, Mustafa (2018-10-01) A coordinate transformation based finite element method is presented for detecting contours of breast cancer tissues in the context of microwave imaging. The geometry and location of a single or multiple cancerous tumors inside a breast tissue are identified by constructing an inverse problem based on the genetic optimization algorithm. The expensive forward solution phase during repeated cost function evaluations is accelerated by placing a transformation medium inside the finite element mesh. This allows ...

Citation Formats

F. Tatar, “Three dimensional finite difference time domain simulations on harmonic motion microwave doppler imaging method using realistic tissue models,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Electrical and Electronics Engineering., Middle East Technical University, 2019.