Method and apparatus for dynamic focusing in ultrasonic imaging

摘要

A dynamic focusing apparatus and method for ultrasonic imaging, using transducer frequency encoding technique to map different positions of the surface of a transducer to different frequency responses. To a particular focal position, the time delay required for focusing from various positions on the transducer surface to the focal point can be calculated. By combining frequency responses and time delays that correspond to different transducer positions, a single transmit waveform can be used to drive the transducer and to realize focusing similar to that of an array imaging system. Similar principles can be applied to dynamic focusing at the receive end. A filter can be used to select particular positions on a transducer surface. The received signal extracted in this manner can also be time delayed for focusing. By combining all filters that correspond to different transducer positions, dynamic receive focusing can be implemented using a single position dependent filter.