In-vitro study of a computed ultrasound imaging method

In the present computed ultrasound holography method a target is scanned with a wide-angle beam in a monostatic manner. Numerical image focusing takes place in the spatial frequency domain using efficient FFT-based algorithms. The beam is formed using 9 elements of a 3.5 MHz phased array. This results in a -12 dB angular aperture of 30 degrees when Blackman-Harris window was chosen as the weighing function for aperture apodization. The side lobe level of the beam could be depressed to -50 dB. The -6 dB spatial resolution was about 1 mm and uniform in a large depth range. By adopting an interpolation scheme the side-lobe level of the point-spread-function could be reduced to 40 dB. The enhanced image quality is demonstrated with in-vitro images of a liver-mimicking phantom and a fresh liver sample