Research On The Technique Of Ultrasonic Blood Flow Detection And Imaging

In recent decades, the medical ultrasound technology has been developed rapidly. As oneof the four major medical imaging technology, ultrasonic blood flow imaging technology is animportant application of ultrasound in the medical field. With the unique advantages ofnon-invasive, real-time, simple and fast, it plays an important role in the field of clinicalmedicine. However, under the premise of safety standards prescribed by the country,ultrasonic blood flow imaging system has been challenged in image quality. It hasincreasingly high requirements for imaging devices. With the rapid development of computertechnology and microelectronics technology, ultrasonic blood flow imaging equipment have adeeper development. Some new signal processing techniques and methods are applied toultrasonic blood flow imaging.This paper first describes the theoretical basis of the ultrasonic blood flow detection, aswell as three kinds of ultrasonic Doppler blood flow imaging technology, ultrasonic spectrumDoppler blood flow imaging, color Doppler blood flow imaging and power Doppler bloodflow imaging. Traditional single-pulse excitation signal have such shortcomings like lowaverage power, low SNR and so on. To make up these shortcomings, this paper discusses indetail the principle of coded excitation and pulse compression technology and select chirpsignal as the excitation signal. Chirp signal can improve the SNR of echo signals without lossof accuracy and increase blood flow imaging quality.The current ultrasonic blood flow detection and imaging systems have the problems ofsignal not matching channel, and have shortcomings of traditional blood flow estimationalgorithm. This paper uses a combination of ultrasonic chirp blood flow imaging methodbased on channel matching to solve the problems above. In order to solve the problem that theprobe transducer cannot match the output, this paper gets a frequency response characteristicby measuring transducer and according to the characteristic to select the transmissionparameters of the chirp signal. This method can effectively improve the output performance,and achieve optimum output effect. The paper also discusses the unique advantages of adaptive MTI filter which can update the filter parameters dynamically according to thechange of wall signals. To solve the problem which cannot be solved by the traditional filter,the adaptive MTI filter makes the system more flexible.Finally, for the traditional blood flow estimation algorithm existing shortcomings like thelimit of maximum measurable speed, the accuracy not high enough and complexity ofimplementation, this paper discusses the blood flow estimation algorithm based on thecross-correlation. The algorithm was used to estimate blood flow velocity with high precision,high efficiency and ease of implementation. It can meet the blood flow detection and imagingsystems’ requirements of accuracy and real-time.