Research On Adaptive Virtual Source Imaging Using The Sequence Intensity Factor

Medical ultrasound imaging technology,X-CT,MRI and nuclear medical imaging(PET,SPECT)have been recognized as four major modern medical imaging technologies,which have become irreplaceable pillar of modern medical imaging technologies.Medical ultrasound imaging technology using the physical characteristics of ultrasound and combined with the electronic engineering technology,computer signal processing,image processing and display technology to achieve the purpose of human tissue structures imaging.Ultrasound imaging is favored by people because of its non-invasive,easy operation,no contraindication for patients,low cost,good imaging performance and convenience.Researchers have been constantly investigating for years to get better ultrasound imaging quality.Virtual source imaging is a beamforming method that views the focus points as virtual elements.This method avoids the storage of a large number of low-resolution signals so that reduces the imaging complexity,while improving the detection depth.However,in the virtual source imaging process,the superposition of low-resolution signals is difficult to meet the requirements of coherence superposition,and the superposition of non-coherent signals will increase the sidelobe level.In addition,the poor imaging quality of the near-field is not conducive to the analysis application in virtual source imaging,so the imaging quality can be improved by adaptively weighting the VS imaging.In this paper,virtual source algorithm is carried out in simulation using Field II to study the effects of different effective apertures,different depths of focus and different number of transmitted pulses on VS imaging,and the best research parameters are proposed.Based on the study of adaptive weighting factors such as Coherence Factor(CF)and General Coherence Factor(GCF),a Sequence Intensity Factor(SIF)for virtual source imaging is proposed.In the process of virtual source imaging,an effective sound field sequence is obtained according to the effective sound field where the virtual array element is located.The sequence contains the echo signal of the target imaging point.According to the characteristics of the effective sound field sequence,SIF enhances and weakens the signal.The partial sequence signal of the imaging point with strong echo signal is enhanced,and the partial sequence signal with weak echo signal of the imaging point is weakened.By weighting the virtual source imaging result of target scatter point,the contrast and lateral resolution of image can be improved.The feasibility and effectiveness of the SIF weighted VS algorithm are verified by comparing the imaging results of various algorithms in simulation and experiment.The clinical significance and practical value of the method were verified by comparing the imaging result of human arteries.