Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2013
Öğrenci: CAN BARIŞ TOP
Danışman: NEVZAT GÜNERİ GENÇER
Özet: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 stage by making use of the contrast between elastic and electrical properties of healthy and malignant tissues. A small vibrating region is created inside the tissue using the radiation force of focused ultrasound waves. A microwave transceiver is used to collect data from the vibrating region at the Doppler frequency, which depends on both elastic and electrical properties. The vibrating region is scanned inside the tissue to generate images. A semi-analytical formulation for the forward problem is developed using a two-layered simple breast model. A three dimensional Finite Difference Time Domain (FDTD) method is developed for analyzing the scattered signal from a vibrating region inside the tissue. Forward multi-physics problem is solved numerically with successive acoustic, mechanical and electromagnetic simulations. The performance of the method is investigated using both homogeneous and realistic numerical tissue models. Phantom materials that mimic the electrical and elastic properties of the fatty, fibro-glandular and malignant breast tissues are developed. The proof of concept is demonstrated experimentally on breast phantom materials using general measurement devices. A 5 mm diameter tumor phantom inside fibro-glandular tissue phantom was identified at 25 mm depth. Simulation results show that even smaller tumors can be detected inside breast issue if specialized receivers and transmitters are used. Even though the performance of the method is investigated for breast tumor detection in the scope of this thesis, it can be used for detecting tumors in the other organs that are microwave and ultrasound penetrable.