Theoretical analysis of equivalency of high-power diode laser (810 nm) and Nd:YAG laser (1064 nm) for coagulation of tissue: predictions for prostate coagulation

Abstract

Profiles of light, temperature, and thermal damage distributions in tissue based on measured optical properties are examined theoretically for high power diode laser (810 nm) and Nd:YAG laser 1064 nm). Generally higher absorption and effectively lower optical penetration has been experimentally observed at the wavelength of diode laser as compared to that of Nd:YAG laser. Results of this study indicate that similar thermal damage volumes are expected to be obtained by the two lasers, in general. However, for same irradiation conditions a larger volume of damage and more charring near the surface is predicted when using the diode laser on prostate tissue, and similarly for myocardial tissue. Role of blood presence throughout tissue, in terms of its optical interaction, as well as the role of a small layer of blood between the laser and the tissue is also investigated for both wavelengths.