Real time imaging with the Sonic Window: A pocket-sized, C-scan, medical ultrasound device

The Sonic Window is a pocket-sized, C-scan ultrasound device designed to expand ultrasound into clinical settings and applications that have yet to benefit from its utility. The low component cost, compact form factor with integrated 2D transducer array, and an intuitive C-scan image format displayed directly over the anatomy of interest are what distinguish this device from conventional ultrasound systems. A prototype of the Sonic Window was designed and constructed consisting of a fully sampled 60 × 60 transducer array, custom integrated circuits (ICs) containing 3,600 front-end receive channels, a high-voltage transmit circuit, an off-the-shelf digital signal processor (DSP), and a liquid crystal display. The 2D transducer array was fabricated on one side of a 2-layer PCB and the front-end ICs were attached onto the other side using a flip-chip process. The front-end ICs acquire the data for one C-scan slice per transmit event and send digital data to the DSP, which uses the Direct-Sampled In-phase Quadrature (DSIQ) method for efficient beamforming. The prototype fits in a 6-cm × 15-cm × 3.5-cm enclosure containing a 1500 mAh rechargeable battery and weighs 6 oz. (170 g). It can form real-time C-scan images at 43 FPS with a 2-hour scan time on battery power. Real-time volume capture enables B-mode image formats as well as 3D imaging. Lateral resolution is approximately 0.75 mm and cystic contrast is 43 dB. Phantom target and in vivo images are presented to demonstrate the imaging capability of the device.