Terahertz Spectroscopy Properties Of Skin Cancer Tissue

In recent years, terahertz science and technology draw more and more attention. Terahertz time-domain spectroscopy (THz-TDS) technology is a new type of coherent far-infrared spectroscopy technology. In the 21st century, biological and medical research is one of the most active areas in the study of human science and technology. Terahertz wave has many advantages becaues of its special frequency band in the electromagnetic spetrum. The wave corresponding to biomolecules vibrational and rotational energy level lies in THz band. Therefore, THz wave has been widely used in biological tissues research. Besides, it has great potential in non-destructive diagnosis of cancerous tissue.THz spectral characteristics and the application of terahertz is introduced in this paper. It can be used in label-free detection of DNA and the vibration spectrum of amina acids and other biomolecules. Some research problems in biological field is pointed out. Particularly the effect of“water”on terahertz is concerned. The influence of different water content is verified by experiments.Based on the THz wave differentitation of human healthy and lesion tissues, terahertz spectroscopy and spectral imaging technique research is conducted to distinguish human skin cancer.First of all, paraffin embedded and fresh normal and skin cancer tissues are detected in transmissive terahertz time domain spectroscopy system. Terahertz time domain spectroscopies are acquired, which are carrying the sample information. By comparing the different sample points spectroscopies, the amplitude can reflect the different tissues in some degree. By Fourier Transform (FFT), the frequency domain spectrums of the sample are gotten. The absorption coefficient and refractive index are calculated, both of which refelect the nature of the sample. As for the different samples, the frequency band , which can distinguish the cancerous and non-cancerous region,shows some difference. For example,the absorption coefficient at 1.4THz can distinguish the healthy tissues and disease of sample 1, as for sample 2, the absorption coefficient at 1.5THz do. After scanning the whole sample, parameters in different frequency bands are selected to generate images, which are used to be compared with pathological diagnosis. The result shows that THz-TDS imaging can give a ressonable result for the diagnosis. For further information, the data is processed by pattern recognition. Principal component analysis is used for dimensionlity reduction. At the same time, PLS method is used to build a model to distinguish cancerous and healthy tissues.The data in the band between 1.4THz and 1.7THz build the most effectively model, the related coefficient can reach 0.983148.