Real time diffuse reflectance polarisation spectroscopy imaging to evaluate skin microcirculation

Abstract

This article describes the theoretical development and design of a real-time microcirculation imaging system, an extension from a previously technology developed by our group. The technology utilises polarisation spectroscopy, a technique used in order to selectively gate photons returning from various compartments of human skin tissue, namely from the superficial layers of the epidermis, and the deeper backscattered light from the dermal matrix. A consumer-end digital camcorder captures colour data with three individual CCDs, and a custom designed light source consisting of a 24 LED ring light provides broadband illumination over the 400 nm -700 nm wavelength region. Theory developed leads to an image processing algorithm, the output of which scales linearly with increasing red blood cell (RBC) concentration. Processed images are displayed online in real-time at a rate of 25 frames s -1 , at a frame size of 256 x 256 pixels, and is limited only by computer RAM memory and processing speed. General demonstrations of the technique in vivo display several advantages over similar technology.

Comparison of instruments for investigation of microcirculatory blood flow and red blood cell concentration

“…Offline, the temporal resolution can be increased to 25 fps at 720ϫ 576 pixels. 32 Using the video mode, spatial resolution is decreased to 75 m. The system has been evaluated with fluid models of skin tissues to validate its image processing algorithm. Using the system, it is possible to capture an area of skin measuring 15ϫ 10 cm with five million measurement pixels at a device-tissue distance of 5 cm ͑the most recent version has ten million pixels͒.…”