Bilgin, Egemen
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bilgine@mef.edu.tr
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02.05. Department of Electrical and Electronics Engineering
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3
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2
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18
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85
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5
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18
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81
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12
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4
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30
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41
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3
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5
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2.50
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3.42
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2
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| Journal | Count |
|---|---|
| Medical Physics | 2 |
| -- 33rd IEEE Conference on Signal Processing and Communications Applications, SIU 2025 -- Istanbul; Isik University Sile Campus -- 211450 | 2 |
| 2021 15th European Conference on Antennas and Propagation (EuCAP) | 1 |
| 2023 Medical Technologies Congress (TIPTEKNO) | 1 |
| 30th IEEE Signal Processing and Communications Applications Conference (SIU) -- MAY 15-18, 2022 -- Safranbolu, TURKEY | 1 |
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Article Citation - WoS: 3Citation - Scopus: 5Single-Slice Microwave Imaging of Breast Cancer by Reverse Time Migration(Wiley, 2022) Bilgin, Egemen; Cansız, Gökhan; Akduman, İbrahim; Cayoren, Mehmet; Joof, Sulayman; Yılmaz, TubaPurpose Microwave imaging of breast cancer is considered and a new microwave imaging prototype including the imaging algorithm, the antenna array, and the measurement configuration is presented. The prototype aims to project the geometrical features of the anomalies inside the breast to a single-slice image at the coronal plane depending on the complex dielectric permittivity variation among the tissues to aid the diagnosis . Methods The imaging prototype uses a solid cylindrical dielectric platform, where a total of 24 optimized Vivaldi antennas are embedded inside to form a uniform circular antenna array. The center of the platform is carved to create a hollow part for placement of the breast and the multistatic, microwave scattering parameters are collected with the antenna array around the hollow center. The dielectric platform further enhances the microwave impedance matching against the breast fat tissue and preserves the vertical polarization during the measurements. In the imaging phase, a computationally efficient inverse electromagnetic scattering method-reverse time migration (RTM)-is considered and adapted in terms of scattering parameters to comply with the actual measurements. Results The prototype system is experimentally tested against tissue-mimicking breast phantoms with realistic dielectric permittivity profiles. The reconstructed single-slice images accurately determined the locations and the geometrical extents of the tumor phantoms. These experiments not only verified the microwave imaging prototype but also provided the first experimental results of the imaging algorithm. Conclusions The presented prototype system implementing the RTM method is capable of reconstructing single-slice, nonanatomical images, where the hotspots correspond to the geometrical projections of the anomalies inside the breast.Conference Object Differential Microwave Imaging of Cerebral Hemorrhage Via Dort Method(IEEE, 2023) Dilman, İsmail; Bilgin, Egemen; Doğu, SemihBleeding in the brain tissues may cause fatal health conditions and continuous monitoring of the change in this blood accumulation becomes important in the first few hours after the incident. The continuous post-event monitoring aims to detect the variations in the size and the shape of the hemorrhage regions. To this end, the human head is illuminated by non-ionizing electromagnetic radiation, and the scattered field is measured in different time instants. The decomposition of the time-reversal (DORT) method is then used as the microwave imaging algorithm to produce an indicator function. The performance of the proposed technique is assessed via numerical simulations involving a realistic human head phantom. The results suggest that the DORT method is capable of detecting the changes in multiple simultaneous cerebral hemorrhage regions successfully.Article Citation - WoS: 17Citation - Scopus: 18Microwave Imaging of Breast Cancer With Factorization Method: Spions as Contrast Agent(Wiley, 2020) Çayӧren, Mehmet; Coşğun, Sema; Bilgin, EgemenFemale breast at macroscopic scale is a non-magnetic medium, which eliminates the possibility of realizing microwave imaging of the breast cancer based on magnetic permeability variations. However, by administering functionalized, superparamagnetic iron-oxide nanoparticles (SPION) as a contrast material to modulate magnetic permeability of cancer cells, a small variation on the scattered electric field from the breast is achievable under an external, polarizing magnetic field. PURPOSE: We demonstrate an imaging technique that can locate cancerous tumors inside the breast due to electric field variations caused by SPION tracers under different magnetic field intensities. Furthermore, we assess the feasibility of SPION enhanced microwave imaging for breast cancer with simulations performed on a multi-static imaging configuration. METHODS: The imaging procedure is realized as the factorization method of qualitative inverse scattering theory, which is essentially a shape retrieval algorithm for inaccessible objects. The formulation is heuristically modified to accommodate the scattering parameters instead of the electric field to comply with the requirements of experimental microwave imaging systems. RESULTS:With full-wave electromagnetic simulations performed on an anthropomorphically realistic breast phantom, which is excited with a cylindrical imaging prototype of 18 dipole antenna arranged as a single row, the technique is able to locate cancerous tumors for a experimentally achievable doses. CONCLUSIONS: The technique generates non-anatomic microwave images, which maps the cancerous tumors depending on concentration of SPION tracers, to aid the diagnosis of the breast cancer.Article Citation - WoS: 4Citation - Scopus: 5Monitoring of Intracerebral Hemorrhage With a Linear Microwave Imaging Algorithm(Springer, 2022) Dilman, Ismail; Dogu, Semih; Bilgin, Egemen; Akinci, Mehmet Nuri; Cosgun, Sema; Çayören, Mehmet; Akduman, IbrahimIntracerebral hemorrhage is a life-threatening condition where conventional imaging modalities such as CT and MRI are indispensable in diagnosing. Nevertheless, monitoring the evolution of intracerebral hemorrhage still poses a technological challenge. We consider continuous monitoring of intracerebral hemorrhage in this context and present a differential microwave imaging scheme based on a linearized inverse scattering. Our aim is to reconstruct non-anatomical maps that reveal the volumetric evolution of hemorrhage by using the differences between consecutive electric field measurements. This approach can potentially allow the monitoring of intracerebral hemorrhage in a real-time and cost-effective manner. Here, we devise an indicator function, which reveals the position, volumetric growth, and shrinkage of hemorrhage. Later, the method is numerically tested via a 3D anthropomorphic dielectric head model. Through several simulations performed for different locations of intracerebral hemorrhage, the indicator function-based technique is demonstrated to be capable of detecting the changes accurately. Finally, the robustness under noisy conditions is analyzed to assess the feasibility of the method. This analysis suggests that the method can be used to monitor the evolution of intracerebral hemorrhage in real-world scenarios. Graphical abstract: [Figure not available: see fulltext.]. © 2022, International Federation for Medical and Biological Engineering.Conference Object Citation - Scopus: 2Feasibility of Distorted Born Iterative Method for Detecting Early Stage of Heart Failure(IEEE, 2020) Akıncı, Mehmet Nuri; Bilgin, Egemen; Joof, Sulayman; Doğu, SemihIn this paper, we analyze the feasibility of using microwaves to detect early stage of congestive heart failure, which causes water accumulation in the lungs. To this aim, a slice from realistic human torso phantom, which consists of all human tissues and organs, is considered. Constitutive parameters of the phantom are calculated by multiple order Cole-Cole model at operating frequency. Then, the scattered field is calculated via method of moment and a 30 dB additive white Gaussian noise is added to create a more realistic scenario. In the solution of inverse scattering phase, distorted Born iterative method is utilized. The presented results show the feasibility of the proposed method.Conference Object Citation - Scopus: 1A Microwave Imaging Scheme for Detection of Pulmonary Edema and Hemorrhage(IEEE, 2022) Ertek, Didem; Kucuk, Gokhan; Bilgin, EgemenThe microwave imaging systems have the potential to present a cost effective and less hazardous alternative to conventional medical imaging techniques. In this paper, a Contrast Source Inversion method based microwave imaging scheme is proposed and tested for the detection of pulmonary edema and hemorrhage. To this end, a realistic human torso phantom is used, and the electromagnetic parameters of the human tissues is determined via Cole-Cole model. The scattered field is simulated via Method of Moments at the operating frequency of 350 MHz, and a 50 dB white Gaussian noise is added to model a realistic measurement setup. The numerical tests performed with the proposed technique suggest that the method can be used to locate the pulmonary edema and hemorrhage, and it is capable of distinguishing these two medical conditions successfully.Conference Object Citation - WoS: 1A Modified Newton Method Formulation for Microwave Imaging(IEEE, 2020) Coşğun, Sema; Çayören, Mehmet; Bilgin, Egemen; Doğu, SemihA new variant of Newton type methods has been developed for quantitative microwave imaging. To deal with the ill-posedness of the inverse problems, standard Newton type methods involve a linearization of the so called data equation using the Fréchet derivative with respect to the contrast function. Here, the formulation is expanded to include the object equation, therefore, the formulation seeks to reduce the errors in both the data and the object equations. While this modification does not remove the need to solve forward problem at each step, it nevertheless significantly improves convergence rate and the performance. To assess the efficiency of the proposed technique, numerical simulations with synthetic and experimental data have been carried out. The results demonstrate that the proposed variant outperforms the standard Newton method, and shows comparable performance to the contrast source inversion (CSI) algorithm with fewer iterations.Article Citation - WoS: 5Citation - Scopus: 5Quasi-Newton Based Inversion Method for Determining Complex Dielectric Permittivity of 3d Inhomogeneous Objects(IEEE, 2022) Çayören, Mehmet; Coşğun, Sema; Bilgin, EgemenWe present a new method for determining the complex dielectric permittivity profile of 3D inhomogeneous dielectric objects from measurements of the scattered electric field vectors in the frequency domain. The method is formulated as a minimization of a cost functional defined in terms of electric field integral equations known as the object and data equations. Instead of an unknown object function containing the electromagnetic parameters of the dielectrics, the contrast sources induced within the scatterers are designated as the unknowns of the inversion scheme to avoid solving the forward scattering problem at each step. Later, the minimization of the cost function is achieved via a limited-memory quasi-Newton scheme, based on the Broyden-Fletcher-Goldfarb-Shanno formula, which iteratively updates the Hessian matrix estimation. The numerical results with the simulated and experimental scattered electric fields demonstrate that the presented method is capable of reconstructing scatterers with complex shapes.Conference Object Frekans Seçici Yüzeyler ile Mikroşerit Yama Antenin Radar Kesit Alanının Azaltılması(Institute of Electrical and Electronics Engineers Inc., 2025) Metin, Ahmet Resul; Aydin, Irem; Bilgin, EgemenIn this study, the radar cross section (RCS) of a microstrip patch antenna was reduced via frequency selective surfaces (FSS). Since microstrip antennas are frequently used in military platforms, antenna design with low radar cross section will contribute to the general efforts towards reducing RCA. First, a microstrip antenna with a center frequency of 5 GHz was designed and a FSS that acts as a reflector at this frequency was developed. Here, the expectation from the FSS is to act as a reflector at the center frequency and to have a transmissive behavior at other frequencies, contributing to the reduction of the radar cross section. By integrating the designed FSS structure into the ground plane of the antenna, RCA reduction was achieved in different bands without shifting the center frequency. According to the simulations, the designed antenna has a 10 dB lower radar cross section in the X band. © 2025 Elsevier B.V., All rights reserved.Conference Object Mikrodalga Tomografi ile Doku İçindeki Yabancı Unsurların Konumlandırılması(Institute of Electrical and Electronics Engineers Inc., 2025) Aydin, Pelinsu; Guler, Gokcenaz; Togar, Ayca; Bilgin, EgemenThe aim of medical imaging systems is to detect harmful elements such as tumors in biological tissues via non-invasive methods. To this end, a low-cost and unharmful microwave tomography system is proposed in this study. S-parameters, which are related to the scattered field, are measured with wide-band Vivaldi antennas placed around the examined tissue. These parameters are calibrated by analytical scattered field to increase data quality. Then, an inverse scattering problem is formulated using them as data and solved via Reverse Time Migration (RTM) and Multiple Signal Classification (MUSIC) methods. This solution produces an indicator function indicating the location of the foreign element within the tissue. The proposed method has been tested with simulations in the CST environment. The results show that the system can successfully detect single or multiple foreign substances in the tissue. © 2025 Elsevier B.V., All rights reserved.
