Mikrodalga tomografi ve meme kanser tespiti

Breast cancer is the second-leading cause of female death around the world. Recent researches in United States and several European countries state that significant number of women face this problem. However, this kind of cancer can be cured with effective treatments if it is diagnosed in early stage. Several breast-screening methods such as X-ray based mammography; ultrasound and Magnetic Resonance Imaging (MRI) exist for breast tumour examination. It should be taken into consideration that screening methods should have high specificity and sensitivity to malignant tumours. Furthermore, these methods have to satisfy some conditions such as comfort of the patient during imaging, high-resolution images for more accurate interpretation, cost and ability to detect the malignant tumours in early stage. The mentioned imaging modalities do not meet all of these conditions simultaneously. A new approach dealing with breast cancer is microwave imaging. Microwave imaging is an iterative nonlinear reconstruction algorithm, which uses electromagnetic radiation with frequencies around 1 GHz. As this method utilizes non-ionizing radiation, it is an efficient and safe technique for breast cancer detection. Principle of this technique relies on the significant contrast between the dielectric properties of tumours and healthy tissues at microwave frequencies. In Tomography technique, different slices of an object are created by measuring the transmitted and reflected penetrating waves to the object. In microwave tomography, the breast is monitored with magnetic field and properties of breast are reconstructed by evaluating the scattered electromagnetic signals. In this thesis work, 24 monopole antennas are placed around the object and scattered field is measured when transmitted waves interact with an object in microwave tomography setup. In the following, different simulations are made by using FDTD method to model the antennas and reconstruction domain. The reconstruction algorithm uses inverse problem algorithm to define a feature of dielectric properties of the target object. Several measurements are performed with current microwave setup for imaging the modelled breast phantoms. Appropriate frequency components and reconstruction setting is evaluated for different large and small objects in several medium. The permittivity of one large object and two small objects were reconstructed successfully. Several breast models including different sizes of tumours were simulated with the existent algorithm. Reconstruction of dielectric properties of simulated data show good agreement with original models.