Research On Acoustic Imaging Algorithm Characterized By Signal Recovery

Medical imaging is one of the most significant technologies in clinical medicine.It can provide the images of internal organs and tissues of human body in a non-invasive way,and has the advantages of easy operation,high repeatability and safety,which provides effective basis for clinical diagnosis and treatment.There are varieties of media in medical imaging,including ultrasound,photoacoustic,X-ray,nuclear magnetic resonance and so on.Ultrasound imaging is mainly based on the acoustic characteristics of target tissue,which leads to more convenience,lower cost and has no radiation.Therefore,it is widely used in disease prevention,diagnosis and treatment.Photoacoustic imaging is based on the photoacoustic effect of target tissue,reflecting the light absorption ability of the tissue which is the medical characteristic different from the one shown in ultrasound imaging.Generally,the process of medical imaging includes signal acquisition and image reconstruction based on the signal.2D imaging is the technology of imaging the target in one specific plane with the received imaging signal,which is the main clinical application and research of medical imaging.2D imaging algorithms include Delay and Sum algorithm and Fourier back-projection algorithm,which are commonly used in Bmode ultrasound imaging and photoacoustic imaging.Delay and Sum is one simple reconstruction algorithm which is easy to implement and can be high parallelized for real-time application.So it is usually used in the imaging system that requires for realtime imaging.Delay and Sum algorithm firstly delays the original signals of different channels of ultrasound transducer respectively and then sums over the delayed signals.With the effective signals strengthened and the noise and sidelobe signals reduced,the reconstructed image is achieved.Based on Delay and Sum,improved algorithms are proposed to increase image quality.However,derived from Dealy and Sum,these algorithms are based on the calculation of one signal value,and can still lead to strong artifacts and sidelobes,which is particularly obvious in photoacoustic imaging.2D imaging technology can dynamically display the target of a 2D plane in real time,but the lack of specific location information greatly limits the accuracy of diagnosis.Therefore,3D imaging technology is used to solve this problem,which can help clinicians achieve rapid and accurate diagnosis,and reduce the evaluation of target shape based on clinical experience.Traditional 3D imaging technology is usually based on 2D image reconstruction.According to the 2D image of each frame and the position of each image in the 3D area,interpolation is performed to reconstruct the 3D image.Compared to 2D reconstruction,more computation makes real-time imaging a major concern in 3D imaging technology.At present,there are still some problems in 3D imaging technology,such as low positioning accuracy,image dislocation and decreased image resolution caused by image interpolation.In this paper,2D and 3D image reconstruction methods are introduced,and a reconstruction algorithm based on acoustic signal recovery is proposed to solve the problems of strong image artifacts and low resolution in traditional algorithms.First,the initial signal of each position in the imaging area is recovered and optimized,and then the image is reconstructed according to the recovered signal.This paper also introduces the reconstruction method based on chessboard positioning,which provides higher positioning and reconstruction accuracy.Experiments including computer simulation,phantom and ex-vivo experiments were conducted to evaluate the performance of traditional and the proposed methods.Also,quantitative analysis and comparison were provided as an effective reference for clinical application.