ENHANCEMENT OF TISSUE LESION DEPTH BY DUAL-WAVELENGTH IRRADIATION WITH THE ND-YAG KTP LASER - PERSPECTIVES FOR LASER PROSTATECTOMY/

The Nd-YAG/KTP laser coagulates and vaporizes prostate tissue. The obj ective of this study was to investigate the combined effects of both w avelengths and to determine the irradiation parameters allowing the la rgest lesion volume. Chicken breast tissue was irradiated ex vivo. Con secutive 1064 and 532nm Nd-YAG/KTP laser irradiations were performed f or different combinations (30 W/10 W, 20 W/20 W, 10 W/30 W) with varia ble total fluence (1200J, 2400J, 3600J) and compared to isofluent sing le wavelengths at 40 W irradiation. The depths, diameters and volumes of the total lesion as well as the vaporization effects of the 532nm w avelength on normal and on priorly coagulated tissue were analysed. Ma ximum total lesion depths (p < 0.001) were found under combined Nd-YAG /KTP (20 W/20 W) irradiation conditions. Ablation efficacy of the 532n m wavelength was reduced after prior 1064 nm irradiation, but crater d epths were increased. Dual wavelength irradiation with the Nd-YAG/KTP laser induces a specific denaturation process. This may represent a ne w approach to increase the depth of coagulation necrosis, and thus the treated volume, thereby improving long-term results.