Study On Ultrasonic Elastic Imaging Of Encoding Excitation

The technology of coded excitation and pulse compression can be used to can be used to solve the contradiction between vertical resolution and depth of investigation, and attracted increasing attention in the field of ultrasound testing. Its practical focus is the way to get the best coded excitation and pulse compression.Ultrasound elasticity imaging, which reveals the elastic properties of tissues and is different with the conventional imaging mode. Depending on the elastic properties of tissue, doctors can get a possible method to discriminate between benign and malignant tumors, and detect early cancer and treatment timely. It makes up for the lack of medical imaging modality, has very important clinical value and broad application prospects, and has become a hot research topic in medical ultrasound imaging.In the applications of ultrasound imaging, the main method of coded excitation is barker codes, Golay codes, Chirp and pseudo Chirp codes. These signals have common characteristics that the power spectrum is close to the white noise in the vicinity of the center frequency of the probe, and the autocorrelation function is close to the S function. Therefore, this paper discusses that coded excitation of the pseudo Chirp and matched filtering technology are used in ultrasound elastography, to compare with the results of barker code and traditional single pulse, and specifically, analysis the SNR and resolution of the various encoding and matched filtering technique in elastography. The following aspects are the main contents of this paper:(1) The characteristics of various coded excitation are discussed, and specifically the characteristics of auto-correlation, matching the transducer and matched filter of single pulse, barker codes, and the pseudo Chirp codes are compared.(2) The SNR and resolution of three encoding signals are discussed.(3) The performance of pseudo Chirp coded excitation and matched filtering techniques in ultrasound elastography is studied, and compare with the single pulse and barker code detection methods. The imaging results of echo signals with three methods used in ultrasound elastography, and the SNR and resolution at two peaks are analyzed.Through this study, we can draw the following conclusions:(1) Pseudo Chirp coded excitation and pulse compression techniques can be applied in ultrasound elastography, and can get better results. (2) Due to the own characteristics of coded excitation, it has interference of side lobe after matched filtering, to a certain extent, and affect the results of ultrasound elastography.(3) Coded excitation and pulse compression technology can get better imaging results in ultrasound elastography, and compared with traditional methods, with the increasing depth of detection, it has a good edge definition, and better SNR and resolution.(4) Compared to the two-phase barker codes, pseudo Chirp coded excitation and pulse compression technology can get better resolution in ultrasonic elasticity imaging.