OPTIMAL BEAM SIZE FOR LIGHT DELIVERY TO ABSORPTION-ENHANCED TUMORS BURIED IN BIOLOGICAL TISSUES AND EFFECT OF MULTIPLE-BEAM DELIVERY - A MONTE-CARLO STUDY

Optimal laser light delivery into turbid biological tissues was studie d by using Monte Carlo simulations based on the delta-scattering techn ique. The goal was to deliver efficiently the maximum amount of optica l power into buried tumors being treated while avoiding potential dama ge to normal tissue caused by strong optical power deposition undernea th the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding n ormal tissue because of selective uptake of the absorption-enhancement dye. The power delivering efficiency to buried tumors was investigate d for various diameters of the laser beam. An optimal beam diameter wa s estimated to achieve the maximum product of the power coupling effic iency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single-beam delivery and The simul ated results showed that with an appropriate dye enhancement and an op timal laser delivery configuration, a high selectivity for laser treat ment of tumor could be achieved. (C) 1997 Optical Society of America.