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Malignant melanoma is the most dangerous oncological skin disease and, as a rule, rapidly progresses, spreading metastases throughout the body. In this way, it is important to diagnose this as early as possible, on early stages. However, this process requires a physician who does not always have enough time and experience to analyze a suspicious neoplasm.
In this research, we have developed a device for dermatoscopic skin examination. The own developed Dermatoscope is based on the Basler acA1920-25uc camera (RGB, 12 bit/px, 1920*1080) has a resolution of ~13 μm/px on the surface of the skin. The device body has been designed and printed on a 3D printer. Tissue lighting is carried out by various LEDs:
• UV: 2 x LEUVA77V20RV00 (365 nm, 1 W, 9 nm half-width);
• White: 4 x LEDs FM-5630WDS-460W-R80 (39 lm, 4000 K) (two polarized LEDs and two unpolarized ones);
• Blue: 2 x CREE XREBLU-L1-0000-00K01 (30 lm, 465-485 nm);
• Green: 2 x CREE XRCGRN-L1-0000-00N01 (52 lm, 520-535 nm);
• Red: 2 x CREE XPCReD-L1-0000-00301 (46 lm, 620-630 nm).
The device takes six pictures during approximately 6 sec with different light on user’s request. Development prototype is 3D printed with ABS plastic. Used lights are white light, white polarized light for deeper skin layers visualization, UV light for fluorescence analysis, three visible colored lights for skin visualization is red, green and blue wavelength ranges which could be used for oxyhemoglobin, deoxyhemoglobin and melanin chromophore mapping.
Using linear polarizing filter allows us glares filtering. Polarizing filter has been used with white light and visible colored lights in the development dermatoscope prototype. It allows us to visualize deeper skin layers and get light absorption at three visible wavelengths without glares influence. The second polarizing filter has been placed on the lens, so all of the filters placed on light sources must be oriented in one direction.
Scattered excitation wavelength light must be filtered while allowing longer wavelengths to pass to get skin autofluorescence images. A 430 nm long-pass filter has been installed on the lens for this purpose.
This device is also equipped with software for automatic recognition of skin melanoma based on texture (Haar wavelet texture features, local binary patterns) and color analysis. In this paper, we present the results of analysis of 225 multispectral images of melanoma and other benign and malignant tumors of the skin in vivo. The dermatoscopy tool analyzes pictures of suspicious areas, highlighting contrast areas of the skin and compares with existing diagnosed cases, which speeds up the accuracy of diagnosis. Using our software, high accuracy (96% sensitivity and 89% specificity) for melanoma has been achieved, which means a principal opportunity of effective excluding similar formations that are not melanoma. Thus, the proposed dermatosocpy tool can be used for screening procedures.
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