4. D-mode ultrasound imaging display
The D-type ultrasonic imaging diagnostic instrument, also known as the ultrasonic Doppler diagnostic instrument, uses the principle of acoustic Doppler to detect and process the Doppler frequency shift signals reflected by the moving organs and blood, and convert them into Signals such as sound, waveform, color, and brightness show the state of movement of the internal organs of the human body. Ultrasound Doppler diagnostic equipment is mainly divided into three types: continuous ultrasonic Doppler (continuous wave doppler) imaging diagnostic equipment, pulsed ultrasonic Doppler (pulsed wave doppler) imaging diagnostic equipment and real-time two-dimensional color ultrasound multiple Color doppler flow image (color doppler flow image) diagnostic instrument.
The continuous ultrasound Doppler imager was the first to be used. It is a transducer in the probe that emits a continuous ultrasonic signal of a certain frequency. When the sound wave encounters the red blood cell group in the bloodstream of the moving target, the reflected signal is already an ultrasonic wave with a changed frequency. Another transducer in the probe converts it into an electrical signal and sends it to the host. After high-frequency amplification, it is mixed and demodulated with the original transmitting frequency electrical signal, and the difference frequency signal is taken out according to the processing and display method. Different, can be converted into sound, waveform or blood flow diagram for diagnosis. This method is difficult to determine the distance and the position of the organs and tissues, which causes a lot of inconvenience to the application of diagnosis.
Pulsed ultrasound Doppler imager emits ultrasonic signals in an intermittent manner, so it is called pulsed. It is controlled by the gate control circuit to generate the transmission signal and to receive and amplify the selected echo signal, and to select the measurement distance by intercepting the time period of the echo signal, and to identify the location of the organs and tissues. Since the transmitted and received signals are pulsed, a transducer in the probe can complete the dual tasks of transmitting and receiving, which can simplify the mechanical structure of the probe, avoid bad coupling between receiving and transmitting signals, and improve image quality All are very helpful. With the adoption and development of pulse Doppler technology, directional detection, spectrum processing and computer coding technology, ultrasonic Doppler diagnostic equipment can not only distinguish the distance, but also determine the direction and speed of blood flow, in various forms Provide diagnostic information to the doctor, so that the measurement level will move from qualitative to quantitative.
The real-time two-dimensional color ultrasound Doppler blood flow imaging diagnostic instrument is the latest scientific and technological achievement in the field of cardiovascular ultrasound Doppler diagnosis in the late 1980s. It combines pulsed Doppler technology with two-dimensional (B-mode) real-time ultrasound imaging and M-mode echocardiography. It displays the blood flow direction and relative velocity on the intuitive two-dimensional cross-sectional real-time image, and provides the cardiovascular system with Information in time and space. Furthermore, through the computer's digital technology and image processing technology, it has the function of physiological monitoring in the framework of the image diagnostic instrument, providing valuable information such as blood flow velocity, volume, flow, acceleration, blood vessel diameter, arterial index, etc. Information; this is commonly known as "color Doppler" or "color Doppler."
