<title>Determination of photosensitizer concentration in normal skin tissue and in skin tumor with the use of two-wavelength laser light</title>

Abstract

Photodynamic therapy of skin tumors requires a technique which enables us to measure photosensitizer concentration in the tissue. This paper presents such a technique. The possibility of using two wavelengths of Kr<SUP>+</SUP>-laser (647 and 675 nm) to calculate the concentration of Phthalocyanine aluminum photosensitizer at different depth in the tissue is discussed. Scattering laser lines and photosensitizer fluorescence intensity with respect to the distance between illumination point and signal output point were measured. A special system has been developed for irradiation of flat surfaces and measuring light intensity. The results are useful in the basic experimental research and in the photodynamic therapy in clinics.