New synthetic aperture imaging technique with dynamic apodization window

Abstract

Synthetic aperture (SA) imaging techniques can enhance spatial resolution in medical ultrasound imaging. However, it suffers from the degradation of image quality close to a virtual source (e.g., transmit focal point) since there is no enough transmit acoustic field energy. In this paper, a new SA imaging technique (i.e., dynamic synthetic aperture, DSA) where the number of synthetic scanlines for acoustic field superposition is dynamically adjusted based on the transmit acoustic field analysis. For the DSA technique, the dynamic apodization window function was generated from the Field II simulation and applied in the phantom and in vivo experiments. The raw radio-frequency (RF) data for phantom and in vivo experiments were captured by an Ultrasonix's SonixTouch research platform connected with a SonixDAQ parallel acquisition system. From the phantom experiment, the proposed DSA method shows the enhanced spatial resolution over the depth compared to the conventional receive dynamic focusing (CRDF). In addition, it doesn't yield any artifacts associated with the lack of enough transmit acoustic energy shown in the conventional SA imaging technique. The consistent results were obtained with the in vivo breast data. This result indicates that the proposed DSA method could be used for enhancing image quality of medical ultrasound imaging.