B-type ultrasound diagnostic technology (abbreviated as B-ultrasound) was used for medical clinical diagnosis in the 1950s and has now developed into color Doppler blood flow imaging diagnostic technology. B-ultrasound is developed on the basis of A-type ultrasound diagnostic technology (abbreviated as A-ultrasound). A-type is a one-dimensional ultrasound diagnostic technology, which displays the echo information of the tissue distributed by distance at the propagation position of the sound beam on the display in the form of amplitude modulation, and diagnoses based on the amplitude, shape and position of the echo. B-type imaging technology displays the ultrasound echo information (scattering and reflection echo information in the tissue) on a cross-section layer of the tissue in the form of brightness modulation in a two-dimensional distribution on the display, and uses the image to determine the corresponding tissue position for diagnosis.

B-type ultrasound diagnostic instrument is widely used in the contours of internal organs and their internal structures, superficial organs, tissue detection, diagnosis, and postoperative observation and treatment due to its unique non-invasive inspection technology, rich information, grayscale cross-sectional images, close to the real anatomical structure, and dynamic real-time display of active interfaces.

1. Structure and working principle of B-ultrasound

(I) Structure of B-ultrasound.

B-ultrasound is developed on the basis of A-ultrasound. Its internal structure and working principle are basically the same as those of A-ultrasound. It is also composed of main control circuit, transmitting circuit, receiving circuit (high-frequency signal amplifier, video signal amplifier), scanning generator, image display (electron gun, deflection system, fluorescent screen) and transducer. The difference between the two is:

(1) B-ultrasound changes the amplitude modulation display of A-ultrasound to brightness modulation display.

(2) The time base depth scanning of B-ultrasound is added to the vertical direction of the display, and the process of scanning the subject with the sound beam corresponds to the displacement scanning in the horizontal direction of the display.

(3) In the various links of echo signal processing and image processing, most B-ultrasounds use special digital computers to control the storage and processing of digital signals and the operation of the entire imaging system, which greatly improves the image quality.

(II) Working principle of B-ultrasound.

B-ultrasound imaging diagnosis is based on the principle of ultrasonic transmission and reception, and is processed by electronic circuits and computers to form B-ultrasound images.

The working principle is as follows: first, the probe (i.e., transducer) of the ultrasonic diagnostic instrument is used to convert electrical energy into acoustic energy to generate ultrasonic waves. When the ultrasonic beam enters the human body and encounters two different media, it will produce reflection, refraction, scattering, transmission, diffraction, and attenuation at the interface of the interface, which is called echo. The remaining energy continues to penetrate deeper and will reflect again when it encounters the interface of different media, and so on. B-ultrasound mainly uses backscattered echo imaging. Reflection occurs at the interface and scattering occurs inside the tissue. The ultrasonic diagnostic instrument then recycles the echoes of various layers of tissue in a certain part of the human body into the instrument through the probe. B-ultrasound displays the echo signal in the form of light spots. Strong echoes are bright, and weak echoes are dark. Ultrasound is emitted at different interfaces to obtain echoes at different times to determine the different distances of the interface. By moving the probe, the inspection site is scanned in multiple sections, that is, the emission beam moves, and each of its echoes produces a light spot on the fluorescent screen, and its position corresponds to the position of the interface where the reflection occurs. To form a series of real-time cross-sectional display images, B-ultrasound is also called a cross-sectional imager or a two-dimensional imager.