Jeong Cho

A mobile medical device for point-of-care applications

Portability and networking ability of medical diagnosis devices are key to point-of-care (POC) and patient-oriented services. We have recently developed a prototype of full custom small ultrasound scanner by implementing an efficient beamforming algorithm, post-processing optimization and low power design technique in FPGA. It can provide B-mode and color flow images using 32 real active channels or 64 effective channels on receive. An embedded CPU and Linux were used for the OS of this device. The POC system also has a Bluetooth module to provide various bio signals which are obtained wirelessly from various biomedical sensors.

A fractional filter-based beamformer architecture using postfiltering approach to minimize hardware complexity

A novel beamformer architecture using fractional delay filters is proposed and verified through experiments. By performing interchannel summation prior to filtering operation in the manner producing no error, the proposed architecture requires only three four-tap filters for the whole beamformer and four simple demultiplexers per each channel

2K-1 A Hand-Held Ultrasound Imaging System for Point-of-Care Applications

As demands for point-of-care (POC) services have increased in and out of hospitals, more and more attention has been drawn to developing portable medical diagnosis systems with imaging capability. We have recently developed a prototype of PDA-type hand-held device which is designed to have the functions and portability required for POC applications by combining an ultra small ultrasound scanner and a full custom PDA using Linux as its OS. The prototype now only supports a phased array but was designed to support various probe types. It is powered by a Lithium polymer battery to achieve the maximum scanning time of about one and half hours. We will present the images obtained with the system and application results of other features. The images will be compared to images obtained from a commercial product using 32 channels in both transmit and receive

New clutter rejection method using time-domain averaging for ultrasound color Doppler imaging

In ultrasound color Doppler imaging, effective rejection of clutter which is originated from surrounding tissues and slowly-moving vessel walls is important to improve the sensitivity in visualizing the blood flow. To adequately remove clutter, highpass filters, such as initialized infinite impulse response (IIR), are typically utilized. In this paper, we present a new clutter rejection method which can provide comparable clutter rejection to projection-initialized IIR filtering while significantly reducing hardware complexity for a low-cost handheld ultrasound system.

A hardware efficient beamformer for small ultrasound scanners

Digital receive beamformer is one of the most important parts governing the performance and complexity of a medical ultrasound imaging system. In this presentation, we present a hardware efficient digital beamformer for small size ultrasound scanners, which is advantageous over the two most widely used beamforming schemes, interpolation beamformer and phase rotation beamformer, in terms of hardware complexity and performance. Interpolation beamformer requires a multi-tap interpolation filter for each channel to obtain 1/16f0 delay resolution. Phase rotation beamformer requires IQ demodulation and performs inter-channel delay compensation by shifting the phase of inphase and quadrature components. The proposed beamformer is identical to the interpolation beamformer except that it uses fractional delay (FD) filters to generate the delayed samples. FD filters were designed using least square error method to obtain an optimum performance for a given hardware complexity. The results show that the proposed method outperforms other beamforming methods.