[Clinical evaluation of ultrasound hyperthermia system]

We studied clinically ultrasound (US) hyperthermia system developed in Japan. The prototype system consists of a power delivery unit (0.5MHz frequency) and a coolded water bolus. The modified type has three frequency applicators (0.5, 1.0, 1.5MHz) with a secondary bolus. Thirty-four patients with recurrent or metastatic tumors located in the shallow tissues were treated. Fourteen patients (Group I) were treated with the prototype system and 20 patients (Group II) with the modified type. In 13 of the Group II patients, aluminum-urethane shields were used to protect nearby bone from overheating. The heating goal was 42.0 degrees C for at least 30 minutes in the tumor's center. The temperature was raised to 42.0 degrees C in 7 of 14 cases (50%) and in 17 of 41 sessions (41.5%) in Group I. In Group II the temperature was raised in 19 of 20 cases (95.0%) and in 67 of 80 sessions (83.7%). Response rates were 50.0% and 75.0% respectively in Groups I and II. The incidence of side effects including burn and ostalgia were 100% and 20% respectively in Groups I and II. These results suggest that the modified US hyperthermia system was valuable in clinical use.