High-intensity focused ultrasound (HIFU) is widely used for therapeutic applications because it is an attractive and non-invasive tool by which to provide thermal therapy. Focus position control of HIFU using multi-elements phase control is very popular in clinical application. However, multi-elements driving amplifier are very large size like a large refrigerator. So, we adopted a direct drive amplifier system for the multi-element transducer. This system has an advantage that it reduces the energy loss of the connecting cable between the transducer element and the amplifier. So, we make the very compacy multi-elements transducer system combined with multi-elements amplifier. In this study, we evaluate the first prototype module transducer. The transducer formed a focal point by the phase control. We measured the acoustic pressure distribution near the focal point and the change in sound pressure level to the input voltage. As a result, the transducer system was confirmed that proper acoustic pressure rise and focus formation by the phase control.
