Local fluorescence spectroscopy and detection of malignancies using laser excitation at various wavelengths

Comparative study of the sensitivity of the local fluorescence spectroscopy in the detection of malignancies with a size of 1–7 mm is performed for various fluorescence excitation wavelengths of the injected photosensitizing agent. Several algorithms for the calculation of the fluorescence contrast of malignant lesion against the adjacent uninvolved tissue are analyzed using the Sarcoma 37 experimental tumor model. The photosensitizers from the Porphyrin (e.g. the 5-ALA-induced Protoporphyrin IX) and Chlorin (e.g. Chlorin e6) families are selected as the fluorescent marker of tissues. Three laser sources with radiation wavelengths of 408, 532, and 635 nm which fall in the absorption bands of Porphyrins and Chlorines are used for the tissue fluorescence excitation.