Light dosimetry: effects of dehydration and thermal damage on the optical properties of the human aorta.

The influences of dehydration and thermal damage on in vitro optical properties of human aorta were studied. The absorption coefficient increased by 20-50%, especially in the visible range when at least 40% of total tissue weight was lost as a result of dehydration. The reduced scattering coefficient increased by 10-45% in the visible and 30% to over 150% in the near IR after the tissue samples were heated in a constant temperature water bath at 100 degrees C for 300 +/- 10 s. This study implies that dehydration and protein coagulation during photothermal treatment of tissue are important factors altering optical properties of tissue.