‘In-house’ Diffuse Reflectance Spectroscopy
Diffuse reflectance spectroscopy (DRS) utilizes white light with a known spectrum, which is guided to the surface of the skin via an optical fiber. As light penetrates into the tissue, photons either scatter or become absorbed where only a fraction of the injected photons manage to escape back from the skin surface. This light is captured by a second fiber and measured with a spectrometer. Depending on the chromophores in the tissue causing the absorption, the measured spectrum will change, from which one can draw some conclusions on the abundance of absorbing species in the tissue, such as oxygenated and deoxygenated haemoglobin.
The extended wavelength diffuse reflectance spectroscopy (EW-DRS) setup has the same working principle as the commercial moorVMS-oxy oxygen monitor. In the novel method developed by Nina Reistad, the wavelength range is extended to the near infrared (NIR) spectral range which allows deeper penetration of photons into the tissue. Moreover, being able to change the separation between the fiber bringing the light to the skin surface and the fiber detecting the transmitted light can be changed, it allows for more selectivity in the tissue depth that is probed. The EW-DRS setup is modular consisting of a range of reflection probes (housing the two fibers) and spectrometers (determining the spectral range), which allows for great flexibility in obtaining detailed information on the molecular composition of the tissue. With this tool, we are constantly developing new software for controlling the acquisition and algorithms, such as spectral unmixing, for providing live feedback on various spectral signatures of tissue differentiation.
The instrument is located part of the time at the Department of Physics and part of the time at the Department of Ophthalmology in Lund and is managed by Associate professor Nina Reistad.