The segmentation of liver using computed tomography (CT) data has gained a lot of importance in the medical image processing field. In this paper, we present a survey on liver segmentation methods and techniques using CT images, recent methods presented in the literature to obtain liver segmentation are viewed. Generally, liver segmentation methods are divided into two main classes, semi-automatic and fully automatic methods, under each of these two categories, several methods, approaches, related issues and problems will be defined and explained. The evaluation measurements and scoring for the liver segmentation are shown, followed by the comparative study for liver segmentation methods, pros and cons of methods will be accentuated carefully. In this paper, we concluded that automatic liver segmentation using CT images is still an open problem since various weaknesses and drawbacks of the proposed methods can still be addressed.
This paper presents an initial investigation for breast cancer detection using a special mode of bistatic radar system known as Forward Scattering Radar (FSR). The proposed method analyzes the Doppler frequency in the received signal scattered from the tumor for cancer detection and localization. Three systems of architectures were analyzed which determined by the mechanical movement of transmitter or receiver or both. This paper also discusses an initial simulated result by using CST Microwave Studio as a feasibility study of utilizing FSR for breast cancer detection. It is shown that by investigating the unique character of Radar Cross Section (RCS) for breast tissue and tumor of FSR a cancer can be predicted. Electromagnetic model including fatty tissue and a tumor were simulated to obtain RCS parameter and analyzed as well as compared with whose fatty tissue without cancerous lesion to pinpoint the presence of tumor from its FSR signature. The result shows a significant different between these two models in FS RCS.
This paper presents a Dual-sideband Optical Carrier Suppression (DSB-OCS) technique which is used to generate an optical millimeter-wave (mm-wave) signal in radio over fiber (RoF) systems. The proposed system employs a Dual-Electrode Mach-Zehnder Modulator (DE-MZM) and a carrier of 40 GHz mm-wave for data transmission through the RoF systems. Characteristics determining the performance of the system, among which are the modulation index, phase imbalance and dispersion parameters, are included. The performance evaluations of the system show that the mm-wave signal output power follows MZM’s transfer function when the modulation index is raised. Moreover, the generated optical mm-wave signal power is affected by phase imbalance and optical splitting ratio. It is observed that the optical fiber dispersion influences the DSB-OCS system by decreasing the amplitude of the mm-wave and the signal-to-noise ratio (SNR).
In this study, we examined the effect of phase noise on the optical millimeter-wave (mm-wave) signal in a dense wavelength division multiplexing radio-over-fiber (DWDM-RoF) system. A single modulator was used to generate the optical mm-wave signal in the DWDM-RoF system. This paper addresses the impact of phase noise, which results from phase imbalance, on the optical mm-wave signal. To lower the effect of phase noise on the optical mm-wave signal, the phase imbalance should be controlled. The phase imbalance can be controlled and decreased by adjusting the phase at the phase shift (PS). The system performance was analyzed using various parameters such as bit error rate (BER), signal-to-noise ratio (SNR), optical signal to noise ratio (OSNR), and error vector magnitude (EVM). From the results, we found the phase imbalance affected the optical mm-wave signal due to the imbalanced splitting of the signal intensity at the MZM. The phase imbalance impacts the phase noise, which impacts the optical mm-wave signal. The phase noise could be decreased by controlling the phase imbalance at the phase of 5π/12. The best results at the phase of 5π/12 were collected for phase noise at 0.02 degrees.
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