Ultrasound is deep-heating form and more depth-efficient than infrared lamps and lasers, but its depth effectiveness is limited. The most commonly frequency used are 1 MHz (wavelength 1.5 mm) and 3 MHz (wavelength 0.5 mm). The velocity of ultrasound in water and tissues of high water content is close to 1500 m/s
Ultrasound device consists of high frequency oscillator, power amplifier and piezoelectric crystal. The oscillator produces high frequency sinusoidal AC, and amplified and applied to the piezoelectric crystal causing it to vibrate at the same frequency (with changing its thickness). This crystal can vibrate at certain frequency (resonant, or natural). This natural frequency depends on thickness of the crystal.
Ultrasound imaging uses sound waves to produce pictures of the inside of the body. It is used to help diagnose the causes of pain,
swelling and infection in the body’s internal organs and to examine a baby in pregnant women and the brain and hips in infants. It’s