[Dosimetry using the right angle firing neodymium: YAG laser fiber for treating canine prostate]

For assessment of the dosimetric and optimal efficacy of Visual Laser Ablation of the Prostate (VLAP), depth, surface area and volume of thermal penetration of the prostate were determined in 14 adult canines. All prostates were irradiated using the right angle laser fiber (Urolase, Bard, USA) with neodymlum (Nd): YAG laser application. In Group 1 animals, treatment was conducted at 40 watts for 60 seconds (2400 jules) and in Group 2, at 60 watts for 60 seconds (3600 jules). Each prostate was dissected out and examined macro and microscopically at 3 days and 1, 2, 4, 8 and 12 weeks after surgery. Mean depth of prostatic penetration, surface area and volume of prostatic tissue ablation in each treatment were 4.75 +/- 1.25 mm, 4.13 +/- 1.13 cm2, 3.39 +/- 1.58 cm3 in Group 1 and 5.75 +/- 1.25 mm, 4.80 +/- 1.95 cm2, 4.36 +/- 1.99 cm3 in Group 2, respectively. Histologically, coagulation necrosis and chronic inflammatory changes of the prostatic stroma became evident in 1 to 4 weeks, and reepithelization in the cavity could be observed at 8 to 12 weeks following the treatment. From these result, it would appear that photoirradiation of canine prostate by the right angle laser fiber brings about cavity formation and that more effective dosimetry with maximum penetration in the canine prostate is possible at 60 watts for 60 seconds of pulse duration. Based on these findings, Nd:YAG laser therapy should find a broader scope of clinical application in the management of benign prostatic hyperplasia.