Popular science knowledge about ultrasound
Whether it's a health check-up or a visit to the hospital, doctors always ask patients to have an ultrasound. Most people's understanding of ultrasound is that pregnant women need B-ultrasound, but in fact, ultrasound is not only used for pregnant women to check the fetus, this is only a small part of the application of ultrasound in clinical medicine. But what exactly is ultrasound? How does it examine the human body?
Ultrasound, that is, ultrasound, is a mechanical wave. The frequency of sound waves that can be heard by the human ear is between 20 and 20 000 Hz. When the vibration frequency of sound waves is greater than 20 000 Hz or less than 20 Hz, we cannot hear them. Therefore, we call sound waves with frequencies higher than 20 000 Hz "ultrasonic". Ultrasonic has the characteristics of good directionality, strong penetrating ability, easy to obtain relatively concentrated sound energy, long distance in water, etc. It can be used for distance measurement, speed measurement, cleaning, welding, gravel, etc., in medicine, military, industry, agriculture widely used.
The ultrasonic frequency usually used for medical diagnosis is 2~10MHz. It can travel through the body and reflect some of it back after hitting different tissues. According to this physical property, scientists have developed various ultrasonic instruments. The ultrasonic wave is generated and emitted by the probe. After entering the human body, part of the ultrasonic wave is reflected back according to the difference in the acoustic properties of human organs and tissues, and then received by the probe and processed by the computer, displayed and traced in the form of waveforms, curves or images. , Ultrasonography is a diagnostic method that an ultrasound doctor can distinguish physiological and pathological conditions according to the characteristics of the image.
