Adaptive Beamforming Algorithm For Synthetic Aperture Ultrasound Imaging

Ultrasound imaging has become a very important imaging method in clinical diagnosis for its non-invasion,non-radiation,low cost,high convenience and so on.However,there are some challenges in ultrasonic imaging.There are many scatterers in the imaging medium,the acoustic clutter and noise produced by the scatterers may lead to the degradation of ultrasonic image quality.Ultrasound beamforming techniques can help to alleviate such problems.Based on the principle and experimental research of different ultrasound beamforming methods,such as delay and sum,minimum variance,etc.Specific studies are as follows:First of all,ultrasound beamforming is a key factor affecting the quality of ultrasound images.Delay and sum is commonly used by traditional ultrasonic image,which can obtain real-time imaging by directly adding the signal data after the time delay.So delay and sum beamforming is still the most commonly used method at present.In contrast,the adaptive beamforming technique can use the recorded wave field to dynamically determine the aperture weight,thus enhancing the axial signal and suppressing the off-axis signal to improve the image quality.In this paper,we simulate and analyze the advantages and disadvantages of adaptive beamforming in synthetic aperture imaging mode,which is very important for us to understand the characteristics and application scenarios of adaptive beamforming.Then,the minimum variance beamforming method of ring array ultrasonic transducers based on synthetic aperture is studied.The traditional linear and arc array only provide limited field of view and its image resolution is non-isotropic,the axial resolution is commonly lower than the lateral resolution.Compared with the linear array,the ring array can provide better resolution,the field of view angle can reach 360°,and the axial resolution is similar to the lateral resolution.Based on traditional minimum variance beamforming,multibeam minimum variance beamforming method for ring array ultrasound imaging is proposed.The results show that the proposed minimum variance beamforming method can effectively improve the resolution and contrast of the ultrasonic image.At the same time,it is proved that the adaptive beamforming method in the ring array has some potential,which can further promote the practical application of the ring array in ultrasound imaging.To sum up,this paper has done systematic research on ultrasonic beamforming,from adaptive beamforming method to minimum variance beamforming of ring array transducers.It can be used for reference to improve the quality of ultrasound image.