P2F-4 High Frequency Coded Imaging System with Full Software RF Signal Processing

Coded transmission is an approach to solve the inherent compromise between penetration and resolution required in ultrasound imaging. It is widely acknowledged that this technique gives major improvement in SNR and enables higher contrast imaging without sacrificing the resolution. Our goal was to examine the applicability of the coded excitation to HF (20-30MHz) ultrasound imaging, especially in dermatology and ophthalmology. A novel RF signal processing platform for research and evaluation of the coded real-time imaging using arbitrary excitation waveforms including (but not limited to) chirp, Barker and Golay codes was designed. The digital programmable coder-digitizer module based on FPGA chip supports coded transmission and RF echoes sampling up to 200MSPS, as well as real time streaming of digitized RF data via a high speed USB interface to the PC. All RF and image signal processing (code compression, scan conversion, visualization) was implemented in the software. The presented system enables the evaluation and optimization of the coded excitation technique both in a laboratory and clinical environment