Research On Ultrasonic Coherent Plane Wave High Resolution Imaging Technology

Ultrasonic imaging is the use of ultrasonic waves in different media will be reflected and scattered,and then according to the echo information can be calculated to obtain an image,so as to achieve the purpose of determining the location of defects or tissues.Because of its low radiation,low cost,strong penetration and high directivity,ultrasonic is widely used in medical imaging and industrial fields.Because of the low frame rate of traditional focused wave imaging,it can’t be real-time imaging.The introduction of plane wave solves the problem of low frame rate,and the whole image of Region of Interest(ROI)can be obtained through one plane wave transmission and reception.However,due to the unfocused plane wave emission,the imaging resolution is low and it is difficult to be directly applied in practical applications.Coherent Plane Wave Compounding(CPWC)is used to stack multiple plane wave echoes to improve imaging quality.However,due to the large coherence between adjacent plane waves,the acquired image still has noise interference to a certain extent.In view of the existing problems,this paper mainly divides into the following two aspects:(1)Based on Coherent plane-wave Composite Imaging,a Multi-array heterogeneous coherent plane wave composite imaging(MAHCPWC)algorithm was proposed,The algorithm uses different spatial positions among multiple arrays to obtain imaging results of the region of interest in different directions.Then,according to the imaging results obtained by arrays in different directions from the standard arrays,a set of weighted vectors is constructed to carry out weighted imaging of CPWC results obtained by the standard arrays.The experimental results show that the coherent plane wave composite imaging algorithm with multi-array heterogeneity can significantly improve the imaging quality compared with the traditional CPWC algorithm.(2)Adaptive weighting technique is often introduced in CPWC algorithm.One of the more common weighting factors is the Coherence Factor(CF),which uses the DC component of the spatial frequency to measure the focusing effect of each array and to modify the CPWC output to improve imaging resolution.However,because CF always overestimates the coherence of the signal,image artifacts are introduced when the signal-to-noise ratio is low,which reduces the background brightness level.Therefore,a Coherent Plane Wave Composite Imaging based on Sub-array Coherence Factor Optimization Weighting(SACF-OW-CPWC)algorithm is proposed in this paper.The algorithm introduced the submatrix into CF to increase the power of coherence factor in increasing the signal-to-noise ratio of images,thereby increasing the robustness of CF.The optimized submatrix coherence factor can reduce the influence of sidelobe on the generated image and improve the final image quality.In this paper,the validity of the proposed algorithm is verified by the data set in the medical Ultrasound Plane-wave Imaging Challenge.