Populaarteaduslikud teadmised selle kohtaultraheli
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.
Meditsiinilise diagnoosi jaoks kasutatav ultraheli sagedus on 210 MHz. See võib liikuda läbi keha ja peegeldada osa sellest tagasi pärast erinevate kudede löömist. Selle füüsikalise omaduse järgi on teadlased välja töötanud mitmesuguseid ultraheliseadmeid. Ultrahelilaine genereerib ja kiirgab sond. Pärast inimkehasse sisenemist peegeldub osa ultrahelilainest tagasi vastavalt inimorganite ja -kudede akustiliste omaduste erinevusele, seejärel võtab sond vastu ja töötleb arvuti, kuvatakse ja jälgitakse lainekujude, kõverate kujul. või pilte. , Ultraheli on diagnostiline meetod, mille abil ultraheliarst suudab pildi tunnuste järgi eristada füsioloogilisi ja patoloogilisi seisundeid.
