Low-Complexity Motion-Compensated Beamforming Engine and VLSI Design for Portable High Frame Rate Ultrasound System

Ultrasonic imaging system provide diagnostic information like tissue images and blood velocity. Compared to other medical imaging systems such as X-ray, computed tomography and magnetic resonance imaging, ultrasonic imaging system has features like non-invasive, non-radioactive, low cost, high frame rate and portable. Related researches have been carried out for long time and widely applied in clinical diagnosis and treatments. Beamforming is one of the most important sub-modules in ultrasound imaging system which could generate B-mode images. It requires considerable hardware resources and computational time. Hence, reducing system cost and increasing the frame rate while keeping good image quality become an important research issue in high frame rate ultrasound imaging system.
Beamforming could be roughly classified into real aperture (RA) and synthetic aperture (SA). Compared to RA, SA is more suitable in high frame rate ultrasound imaging system due to lower complexity and cost. The output image of SA is formed with series of low resolution images (LRIs). It is susceptible to motion, which will cause the inhomogeneous LRIs. In the normal clinics, motion can be reduced by holding breath or compensated by existing off-line algorithm. However, when the system is used on the ambulance, battlefield, or children, motion is difficult to avoid and it will degrade the image quality severely.
To solve above problems, a real time two-dimensional motion compensation algorithm is proposed. Proposed method could reduce computational complexity significantly by geometry characteristics of synthetic transmit aperture, and generate high quality images. Besides, a low-complexity linear array delay-and-sum architecture is proposed. Integrating above features with chip implementation, we have developed a high image quality and motion compensated real-time portable ultrasound imaging system. Real-time and high image quality characteristics are helpful for physicians to immediately evaluate patients, which could improve the healthcare efficiency and quality. The portable and motion compensated characteristics could let the proposed imaging system be used in the ambulance, battlefield or medical promotion in remote areas, and provide a new application-oriented field in medical imaging.