Research Of Millimeter-wave Techniques In Skin Cancer Detection

In recent years, the incidence and mortality rates of skin cancer are rising year by year,seriously endangering the lives and health of people. The early detection of skin cancer can greatly extend the lives of patients. So the early detecting and diagnose of skin cancer is one of the keys for increasing the cure rate. At present, some often-used physics detecting artifices are: X radial, computerized tomography, magnetic resonance imaging and so on, but they are very expensive or harm to human body or discomfort.On the basis of biological tissue dielectric property, this paper do a feasibility study of millimeter-wave techniques in skin cancer detection.Because of the different dielectric characteristics between the body’s normal skin tissues and pathological tissues, so their reactions are different when irradiated by millimeter wave.Therefore the millimeter wave can be used to detect skin cancer according to this reason.At first, it is discussed the dispersion characteristics of the skin and the tumor, and introduced the calculation model of biological tissue dielectric property: debye model,Cole-Cole model, and so on. The calculation formula of dielectric property is obtained at different frequency. At 100 GHz frequency, we can obtain the dielectric characteristics of normal skin tissues and pathological tissues.Next, a dielectric rod waveguide(DRW) antenna is designed based on a standard rectangular waveguide. It is a micro-machined, high-resolution microwave measurement probe with the advantage of low side lobe and radiation power. The contact area of the probe and skin is small, it can detect smaller tumors. A dielectric rod waveguide(DRW) antenna model is designed, and calculated with the XFDTD software based on Finite-Difference Time-Domain(FDTD) method. The structure of DRW antenna is optimized by studying the performance of the antenna.Then, a simplified model for analyzing is founded according to physiological structure of human skin tissue and making use of DRW antenna. The reflection coefficient of normal skin tissue and pathological tissue is analyzed and calculated. Contrasted the reflection of with and without the tumor tissue, it is discussed the influence of theposition and number of the tumor layer on the reflection coefficient. It suggests that mainly the superficial layer have an influenced on the measurement and the measurement will not be influenced by deeper tumor layer. In the range of 102.5GHz to 104 GHz,the reflection coefficient amplitude and phase of skin and tumor tissue are calculated. In the range of 103GHz~103.5GHz, the reflection coefficient amplitude of tumor tissue is bigger than normal tissue, differences in 1d B. The variation range of amplitude is in the range of-7 to-9, have a good detection effect. Compared with similar research, DRW antenna has a high amplitude, it is more beneficial to the detection, improve the detection resolution. The structure of DRW antenna is optimized by studying the performance of the antenna.