Ultrasound machine is used take medical tests that forms live images of the movements happening inside the body. Ultrasound is a medical imaging technique that uses high-frequency sound waves, which are not audible by humans as these sound waves are of higher frequencies than the audible limit of humans. The range of frequencies at which an Ultrasound machine operates varies from 20 KHz to several gigahertz. There are multiple uses of Ultrasound machines in medical field, such as during pregnancy, it is used for measuring the size the size of the fetus and its health, detecting disease in gallbladder, checking blood flow, detecting genital and prostate problems, and more.
Ultrasound Machine Working Principle
Ultrasound machine works on the principle similar to that of SONAR systems used in military and naval applications.
The fundamental principle on which an Ultrasound machine works is
“In an ultrasound machine, high-frequency sound waves are emitted toward the body. As these waves penetrate the skin, they bounce off the inner organs and tissues.”
A device called transducer probe is used to generate and receive sound waves. . It can both emit the sound waves and record the returning echo waves. Transducer Probe works on the principle of “Piezoelectric (pressure electricity) effect,” and it is made up of special ceramic crystal materials called piezoelectrics; this material produce an electric field on the application of sound waves and vice- versa.
During an ultrasound test, a water-based gel is applied on the skin of the body part, which going to be examined by the technician. The gel is applied to prevent the formation of air pockets between the transducer and skin and help in transmission of the sound waves into the body. When the transducer is used with some pressure on the skin, pulses of inaudible high-frequency sound waves travels inside the area of the body part, which is being examined, until they hit a barrier such as soft tissue, bone, fluid, or internal organ. When some of the waves hit a boundary, they bounce off, and small changes in the pitch of the sound and deviation in the direction of the waves is recorded by the sensitive receiver of the transducer. Variation in intensity and shape of echoes depends on how the sound waves are absorbed by the area. Some other waves that did not reach any boundary, they keep travelling until they reach another barrier and reflect back. As the transducer begins to receive signals, computer starts to interpret the signals into a two-dimensional image and display it on the screen. Multiple frames of moving pictures are captured into still images, which are called a sonogram. Images can also be converted into short video loops.
In medical applications, ultrasound waves with frequency ranging between 2MHz to 15 MHz are used. Different frequencies that are used to check different body parts are given below:
- 2.5 MHz frequency is used for abdominal check-up to research about deep abdomen and applications of obstetrics and gynecology.
- 3.5 MHz frequency is used for studying general areas of abdomen and applications of obstetrics and gynecology.
- 5 MHz frequency is used for studying the circulatory system, lymph nodes, pelvic areas, and breasts.
- 7.5 MHz frequency is used to study about breasts and thyroid glands.
- 10 MHz frequency is used to study breasts and thyroid, examine the superficial veins. It is also used for examining body’s musculoskeletal system.
15 MHz frequency is used for medical imaging. It is also used for studying musculoskeletal system and superficial soft-tissue masses.
