Determination of photosensitizer concentration in biological tissues from diffuse reflectance and fluorescence

We present a fiber-optic device for noninvasive determination of the optical properties of biological tissues and photosensitizer concentration. The device developed can be used in two modes: the mode for detection of the spatial distribution of diffuse reflectance, and the fluorescence mode. We tested the device in vitro on specimens simulating tissue and on whole blood, and also in vivo on rats. We have shown that with additional modification and adaptation, the device can be used for in vivo monitoring of parameters important for photodynamic therapy.