A novel 100 watt High Intensity Focused Ultrasound driving system

Ultrasound B-Mode imaging systems are often used to image tissues to which High Intensity Focused Ultrasound (HIFU) is being applied. Since HIFU operates at frequencies in the same range as a B-mode imager, the two technologies interfere when they are simultaneously applied to the patient. This causes the imaging window to “whiteout” and obscure the target region, thus defeating the purpose of using the ultrasonic imager in the first place. The system in this paper controls the interference window by pulsing the HIFU at a frame rate synchronized to the ultrasonic imager. The frame rate is either approximated by using an on-board oscillator, or it is captured from stray electromagnetic waves received from the ultrasound transducer. The system is capable of delivering 100 W of peak electrical output power to a HIFU transducer. It is controlled by a custom software application, and synchronizes with B-Mode imaging systems with frame rates from 10–100 Hz. An on-board Direct Digital Synthesizer generates HIFU RF from 1–5MHz. The complete system provides precision positioning of the interference window in a small and portable desktop package.