前立腺レーザー高温度治療におけるNd: YAGパルス波と連続波レーザーの違いに関する基礎的検討

Abstract

We examined basically the difference between Nd: YAG pulsed and continuous wave (CW) lasers using a phantom which was irradiated by two different fibers (a side-firing fiber; Xintec Corporation, balloon laser fiber; SLT-Japan Co., Ltd.). First, a phantom of pig liver was irradiated using the side-firing fiber which tip was located at 5mm away from the target tissue. The laser irradiation was performed for the period of ten seconds at the laser power of 10, 20, 30, 40 and 50watts, at 40 watts at a dose of 100, 200, 300, 400 and 500 joules, and at 40 watts for the period of 30 seconds. Second, the temperature distribution in a phantom (kamaboko) was observed using a balloon laser fiber. The laser irradiation was performed at 20 watts power for the period of ten minutes, and the temperature was measured at 2.5, 5, 7.5 and 10mm from the balloon surface using a thermocouple. The cavity of vaporization, the width and depth of the lesion, formed by CW laser was larger than that formed by pulsed laser. The width and depth of coagulative lesion by CW laser were also larger than that by pulsed laser, however the thickness of the coagulative lesion was formed thicker by pulsed laser than by CW laser. The temperature in a phantom by laser radiation of both types was mostly elevated at 5mm depth from the balloon surface. The temperature elevation at 7.5mm depth was higher at pulsed laser radiation than at CW laser radiation. From these data, it was thought that the pulsed laser radiation elevated the tissue temperature higher at deeper area from the balloon surface, and thickly formed the coagulative lesion.