Design and realizing of a radar based microwave imaging system for early detection of breast cancer

Breast cancer, in developed, developing and underdeveloped countries, is the highest cancer type among woman with a rate of about 15-16%. Early diagnosis for the treatment of the disease is the most important parameter to save lives. While the rate of the disease is almost similar all over the world, the rate of recovery from the disease is high in developed countries and unfortunately low in developing and underdeveloped countries. The reason for this is the early diagnosis advantage of the healthcare system in developed countries. In the developing countries where our country is included, the people who get sick are acquainted with the disease in the later stages where the fight against disease becomes more difficult. In order to prevent this situation, it is necessary to bring people together with early diagnosis scans while they are not yet caught in the disease or have yet to be new. Nowadays there are methods such as X-ray mammography, ultrasound, MRI, and positron emission tomography (PET) for imaging of breast cancer. However, these methods have some disadvantages. The ionizing effect of x-ray rays in human tissue causes the risk of other cancers. In addition, pressing of the breast during measurement can cause pain. In ultrasound, images are of low resolution and it is not possible to distinguish malignant tumor from benign tumor. MRI is an expensive method and is frightening for people with closed area phobia. It also takes too long. In the PET method, the radioactive material injected into the body carries the risk of causing new cancers by creating an ionizing effect with the emitted gamma rays. The disadvantages of these methods used in the imaging of breast cancer have led to the research and development of alternative imaging methods. Microwave imaging technique is one of these methods. Microwave imaging technique uses backscattered waves arising from the contrast between dielectric properties of normal and tumor tissues. Imaging of the breast tumors in their exact position and with high resolution is one of the most important challenge to be overcome in current imaging methods and in the microwave imaging method. To obtain high resolution and accurate images in radar-based microwave imaging, which is used in this study and is popular among microwave imaging methods, are dependent on some parameters. These are the suitability of the antenna to be used, the number of antennas to be used and the radar measurement system, the performance of the filtering techniques and the performance of the focusing algorithm. The antenna must be compact, ultra wide band (3.1-10.6 Ghz), directional, high gain (as far as possible, in all operating frequency band). Within the scope of this thesis, the antenna design will be realized according to the desired characteristics by using the electromagnetic simulation program and the performance of the antenna analyzed by parameters such as bandwidth, radiation pattern, gain, directionality, group delay and fidelity. After the suitable antennas were designed, homogeneous, semi-homogeneous and heterogeneous breast structures were created in the simulation environment. Measurements were performed in time domain as monostatic, bistatic and multistatic. In monostatic measurement, the same antenna serves as both the transmitting and receiving antenna. As a result of measurements made at different points around the breast, the reflected signals are collected. In the simulation environment, monostatic, bistatic and multistatic measurement systems have been analyzed and results have been presented with their advantages and disadvantages. These results guided which system should be used during the experimental setup of the system. The designed antennas were used as sensors in a microwave imaging system. The performance of the system has been tested with realistic breast phantoms prepared in the biochemistry laboratory that mimic real human tissue, that is, have similar characteristics with the electrical properties of breast tissues. The results obtained show that the developed microwave imaging system that developed in this thesis can be used in early detection of breast cancer. This system is low cost, safe, comfortable and fast.