[Interstitial temperature measurement during balloon lasertherapy (Prostalase) of the canine prostate]

We examined the distribution of interstitial temperatures during balloon lasertherapy, using 4 mongrel canines. The laser equipment (CL50FS, SLT Japan Co. Ltd. Tokyo, Japan) consisted of Nd:YAG laser that produced 360 spindle-shaped radiation from a laser balloon (2 cm long) with a water-cooled circulation system. By measuring the temperature 3-5 minutes after the beginning of the treatment, we obtained following results. The temperature of the bladder neck and urethral sphincter remained below 42 degrees C except under extreme conditions. The temperature at a 6 mm depth from the prostatic urethra rose as laser energy increased, but was not affected by increased circulation of cooling water. The temperature at a 10 mm depth from the prostatic urethra was not affected by either increased laser energy or increased circulation of cooling water. We concluded that the limit of tissue cooling is within 6 mm and direct transmission of laser energy is within 10 mm. Distribution of the tissue temperature peaked at a 6 mm depth in the prostatic urethra. When cooling water was circulated at a 200 ml/min and laser-energy was generated at 30 W, the temperature distribution demonstrated that at a 4-10 mm depth from the prostatic urethra reached over 45 degrees C and at a 6 mm depth from the prostatic urethra, a peak of 52 degrees C was obtained. The possibility of thermotherapy of the prostate was suggested.