IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 04 Issue: 06 | June-2015, Available @ http://www.ijret.org 210 CHEBYSHEV FILTER APPLIED TO AN INVERSION TECHNIQUE FOR BREAST TUMOUR DETECTION Marta A P Elizabeth 1 , Kismet Anak Hong Ping 2 , Nordiana Binti Rajaee 3 , Toshifumi Moriyama 4 1 PG Student, Department of Electrical and Electronic Engineering, Faculty of Engineering, Universiti Malaysia Sarawak,Jalan Datuk Mohd Musa, 94300 Kota Samarahan, Sarawak,MALAYSIA 2-3 Senior Lecturer, Department of Electrical and Electronic Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, Jalan Datuk Mohd Musa, 94300 Kota Samarahan, Sarawak, MALAYSIA 4 Associate Professor, Department of Electrical and Electronic Engineering, Faculty of Engineering, Nagasaki University,1-14 Bunkyo-machi, Nagasaki 852-8521, JAPAN Abstract Microwave imaging has been extensively studied in the past several years as a new technique for early stage breast cancer detection. The rationale of microwave imaging for breast tumour detection is significant contrast in the dielectric properties of normal tissue and malignant tumours. However, in practice noise present from the environments during screening/examination degrades the quality of the image. Inaccurate reconstructed image caused false/misleading interpretation of the image which leads to inappropriate diagnose or treatment to the patient. In the simulation works, noise is added to imitate the actual environment scenario. The two-dimensional (2D) object that identical to breast model is developed using numerical simulation to imitate the breast model. A filter is integrated with an iterative inversion technique for breast tumour detection to eliminate the noise. To assess the effectiveness of this approach, we consider the reconstruction of the electrical parameter profiles of 2D objects from measurements of the transient total electromagnetic field data contaminated with noise. Additive white Gaussian noise is utilized to mimic the effect of random processes that occur in the nature. This paper presents the filter settings and characteristics that affect the reconstruction of the image in order to obtain the most reliable and closer to the actual image. Selection of filter settings or design is important in order to achieve desired signal, most accurate image and provide reliable information of the object. Chebyshev low pass filter is applied in the Forward-Backward Time-Stepping (FBTS) algorithm to filter the noisy data and to improve the quality of reconstructed image. Keywords: Chebyshev low pass filter, microwave imaging and breast tumour detection --------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION Breast cancer is the most cause of death among women. In 2014, an estimated 40,430 breast cancer deaths (40,000 women, 430 men), an estimated 232,670 new cases of invasive breast cancer were expected to be diagnosed, along with 62,570 new cases of non-invasive breast cancer (also known as carcinoma in situ) [1]. X-ray mammography [2], ultrasounds [3], combined [4] and in uncertain cases, with percutaneous (access the tissue by using needle-puncture) biopsy are the existing methods in detecting and screening breast cancer. As reported in [5], the limitations have inspire the researchers to develop another alternative detection method which is relatively safe, inexpensive imaging modality, and has ability to provide reliable and informative results. The main preventative strategy is focusing on the early detection and to improve the survival rates. The last decade had shown significant increase involving microwave based system as reported in [6-10]. Microwave imaging is a technology which has potential application in diagnostic medical field. Microwave screening for breast cancer detection methods have been found to be more comfortable to the patient, low cost of scanning system and safe [11]. The ability to provide high contrast in dielectric properties of normal breast tissues and tumours have resulted in exploration of technique such as electrical microwave imaging via space-time (MIST) beamforming [12, 13], microwave tomography [10, 14] and radar based breast imaging [15-17]. At present, researchers are intriguing in designing and testing the efficiency of imaging system. The inversion method utilizing in time domain for reconstructing the electrical properties has been tremendously developed and improved [18-22]. The inverse scattering technique in electromagnetic has been investigated in various fields such as medical imaging [11], non-destructive evaluation [23-25], target identification [24-26] and geographical exploration [27]. Parallel computing [28] and random boundaries [29] have been applied to increase the efficiency of forward-backward time-stepping (FBTS) reconstruction method as the solution methods to overcome space limitation problem and to reduce the computation time. In previous work in [30] had shown the capability of filtered FBTS applied for cancer breast detection with high contrast between fat and fibroglandular tissue, and low contrast between fibroglandular and tumour tissues. Noise degrades