Parabolic reflection high intensity ultrasound based device with mechanically-variable focusing

The goal of our investigation is to develop a high intensity focused ultrasound (HIFU) device with mechanically-variable focal lengths, achieved by parabolic reflection mechanism. Several configurations of parabolic reflector were simulated using Wave2000 Pro and a custom-developed geometric ray tracing method (MatLab). A cylindrical ultrasound transducer (height 5 cm, diameter 3.7 cm, frequency 2 MHz) was used as the source. Translational and rotational movements of single parabolic reflectors, multiple parabolic reflectors, and segmented parabolic reflectors were considered for their effectiveness in focusing the beam in the range of 5-10 cm. The simulations showed that focusing using a single parabola was achieved with a translation of 14 cm, and a rotation of 25 /spl deg/. Multiple parabola provided optimal focusing with a minimum number of 4 segments. Parabolic reflection mechanism may provide an effective method of a variable-focus HIFU transducer.