Designing and realization of the dynamic filter in digital B mode ultrasonography

This study aimed to obtain the ultrasonic echo images with the best resolution in all detective depth. A dynamic filter was designed based on field programmable gate array (FPGA). The detective depth of the digital B mode ultrasonography was divided into 64 segments, and sixty four 32-step band-pass filters were adopted to complete the process of the dynamic filtering of human ultrasonic echo signals. Then the design was applied to the digital B mode ultrasonography with 128-elements and the center frequency of 3.5 MHz. With the experiments in tissue mimicking ultrasound phantom, the detective depth, the resolution in far field and the denoising ability were all obviously improved compared with the image created by using the constant filter.