Evaluation of chirp and binary code based excitation pulses for 3D USCT

3D ultrasound computer tomography (3D USCT) is a new imaging method aimed at early breast cancer detection. For synthetic aperture focusing the data is acquired with (nearly) unfocussed ultrasound emission and reception. Therefore the SNR of the data is low and needs to be optimized. Pulse compression techniques were scored for the USCT approach: Damped sine pulses (´sinusoid´ pulses), linear chirps, Barker binary codes with 13 elements, Golay code sequences with 16 elements were evaluated. Applicability to the USCT setup and designated application was tested with breast tissue mimicking phantom. Robustness and quality of the different pulses was analyzed with an empty measurement. The evaluation was based on the well-established metrics SNR, GSNR, PSL, and ISL. As overall result, the advanced time compressing techniques form radar are suitable to the USCT setup and the designated medical application. The Golay code showed the highest SNR for empty measurement (56 dB) and the object measurement (42 dB), followed by the Barker code and the chirp pulse. The sinusoid pulse has by far the lowest SNR. The evaluated Golay code is a promising option as excitation pulse for USCT, with downside of a doubled DAQ time. Therefore, the Barker code is also an option for increasing the signals´ SNR.