ヒトセミノーマモデルを用いたレーザー療法におけるパルス波と連続波Nd

(背景と目的) ヒト精巣セミノーマ移植腫瘍に対し, 共通の90度側射ファイバーを使用し, パルス波と連続波発振Nd: YAGレーザー光による温熱効果と組織内温度上昇について両レーザー間で比較検討した. (対象と方法) 担癌マウスを仰臥位で固定し, 水没した腫瘍に対し側射ファイバー反射面より2mmの距離で固定照射を行った. 各群は5匹ずつとし, 照射出力, 時間は, 20W, 180秒照射群, 40W, 90秒および120秒照射群, 60W, 30秒, 60秒および90秒照射群とした. 照射終了後, 移植腫瘍の腫瘍割面像で, 凝固層の深さと幅を測定した. 照射時の組織内温度上昇は腫瘍表面より7, 10, 14mmの距離で両レーザー出力20W, 40Wおよび60Wにて90秒照射し, 経時的に温度測定を行った. (結果と結論) 同エネルギー量3600J, 6群 (パルス波, 連続波: 20W, 180秒照射群, 40W, 90秒照射群, 60W, 60秒照射群) における比較検討でパルス波60W, 60秒照射群 (深さ, 幅, 仮想体積: 平均10.6mm, 12.7mm, 736mm3) がその他のいずれの群より凝固層の拡大を認めた. さらに組織内温度からも明らかにパルス波の良好な熱伝達性が証明された (パルス波60W: 腫瘍表面から7, 10, 14mmの位置でそれぞれ平均96, 77, 40℃). (Background) We report basic animal experimental study which we evaluated the thermocoagulation effects of two different type of Nd: YAG laser (pulse and continuous wave (CW) laser). (Methods) The Rotalase internally reflecting fiber delivery system coupled to the pulse and CW Nd: YAG laser was used to create lesions in Seminoma tissue implanted Scid mice with the fiber tip 2mm away from the target tissue under the water. Laser power output used was 20, 40 and 60-watt for varying times (30-180sec) of irradiation. Stationary lesions, where a single spot of target was irradiated, were created. On the other hand, we measured tissue temperatures at 7, 10 and 14mm from tissue surface. The seminoma tissues removed from Scid mice were photographed after bisection, the fixed in 10% formalin and examined histologically. (Results) For the purpose of these experiments, ablated tissue is defined as the volume of tissue that has been destroyed by both coagulation and vaporization. Estimates of the volume of ablated tissue were made by macroscopic examintion of the bisected lesion, measuring the depth and width of the lesion as seen from the edges of the coagulated area around vaporized zone. The mean depth and width penetration, volume ablation and rising of the tissue temperature at pulsed 60-watt, 60 seconds was greater than that observed at other groups. Irradiated spot lesions were characterized by an initial 10-20 second period of tissue blanching followed by an audible “popcorn phenomenon” which meant more than 100°C in tissue temperature, then formation of small surface bubbles as tissue began to evaporate and char. (Conclusion) This study suggests the potential usefulness of the pulse Nd: YAG laser for Visual Laser Ablation of the Prostate (VLAP).出版者照会後に全文公開 / 許可を得て公