Breast cancer arises either in the lobules or the ducts of the tissue. Structural changes occurring with malignancy manifest as refractive index variations inside the tissue. It is crucial to quantify these depth wise variation in refractive index for early cancer detection. In this study, three types of unstained breast tissue sections - fibrocystic, fibroadenoma, and invasive carcinoma have been examined for the ultra-structural changes using `Fourier domain low coherence interferometry'. The resulting interference spectra of the backscattered light from the front and the rear surface of the sample are Fourier analyzed to provide depth correlation function. The subtle small-scale fluctuations in the Fourier analyzed spectra are then evaluated using Discrete Wavelet Transform (DWT). Daubechies-1 wavelet of DWT is used to calculate the high pass and low pass coefficients. The sixth level low pass coefficients of DWT clearly discriminate among normal, benign, and malignant breast tissue. Skewness and kurtosis values for these coefficients are also able to well distinguish the type of tissues.
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