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3D Ultrasound Computer Tomography (USCT) aims at early detection of breast cancer. The system was optimized for Synthetic Aperture Focusing Technique (SAFT) using unfocused ultrasound transducers. Due to low SNR of the signals, Coded Excitation (CE) and Matched Filter (MF) are applied. For complex objects the received signals (A-scans) consist of multiple overlaid reflections. The overlaid reflections are difficult to separate due to the system's limited bandwidth which results in side lobes. Non-separable reflections limit the resolution and contrast of the resulting images. Using Huffman Sequences (HS) as CE, a trade-off can be set between the side lobe suppression and loss of main lobe energy. Higher suppression of side lobes results in reduced energy in the CE, i.e. smaller SNR. So an approach has been implemented which suppresses the side lobes, but preserves the energy of CE by designing a Huffman sequences based mismatched filter. Combination of a CE and different filters were evaluated for single reflection and multiple overlaid reflections. The results show high side lobe suppression within limited bandwidth and preserve the SNR.

3D USCT II is a new imaging method aimed at early detection of breast cancer. Synthetic aperture focusing technique is used for reconstructing images which requires unfocused ultrasound emission and reception. Thus the SNR received is low. Coded excitation (CE) and match filtering techniques are used to increase the SNR. The Currently applied CE is a linear chirp.