2)
B-ultrasound is an economical, practical, repeatable and nondestructive inspection method. Because of the different density of human tissues, different tissues have different acoustic impedance. When incident ultrasonic waves enter two adjacent tissues or organs, acoustic impedance difference will occur. When this difference is > 0. 1, the ultrasonic wave passing through the interface between two tissues will be reflected and refracted. Therefore, when sound waves pass through, an acoustic interface is formed between the two tissues, and different tissues show different echoes. According to different echo ultrasonic instruments, some diseases of tendons, ligaments, articular cartilage and some bones can be detected, which is an important auxiliary means to diagnose orthopedic diseases.
3) Especially in obstetrics, the application scope has been expanded unprecedentedly, which is of great significance for evaluating whether the fetal structure is abnormal, multiple pregnancy, fetal size, pregnancy cycle and so on. Obstetric B-ultrasound is famous for its three advantages: painless, non-invasive and rapid.
4) It is widely used in clinical diagnosis of diseases in cardiology, gastroenterology, urology and obstetrics and gynecology.