Estimation and Study of Biological Tissues Using Optical Methods

The laser radiation is increasingly applied in therapeutic and diagnostic medicine to detect the abnormal tissue non-invasively and for the treatment of different pathologies in tissues. When this radiation is incident on a tissue, due to mismatch in refractive index at the air-tissue interface, a part of this beam is specularly reflected, whereas, the remaining part enters the tissue. Experimental result using circular saline photons showed the feasibility of the method for biomedical applications such as the study of characterization of biological tissues and wound healing. Because of cellular tissue structure and refractive index variation in the tissues beneath, some photons emerge from the surface (backscattering) and the rests are absorbed in thick complex tissues. In soft tissues such as human breast a part of this beam is also transmitted. The penetration of light within the therapeutic window is more leading to high remittance after deep penetration which could be probed to measure the metabolic, physiologic or possibly structural status of tissues. On the other hand the transmitted component also carries the information on the structural variation but this is partially blurred due to high scattering nature of tissues.