An ultrasound device is a medical imaging tool that uses high-frequency sound waves to produce images of internal body structures. The device is commonly used in medical settings for diagnostic purposes, such as imaging organs, tissues, and blood flow. Ultrasound works by emitting high-frequency sound waves into the body and measuring the echoes that are returned. Sound waves with frequencies exceeding human hearing (> 20 kHz) can be detected. Most ultrasound probes, called transducers, detect frequencies in the range from 2 to ~ 15 MHz. These echoes are used to generate a 2D image of the internal structures of the body, such as the organs, blood vessels, and tissues. Since ultrasound allows us to have real-time images and see internal structures and movement in real-time, it will make it a useful tool for guiding medical procedures.
An ultrasound device consists of several components:
* Transducer probe: This is the main part of the ultrasound machine. It is typically a hand-held device that is placed on the skin. The transducer probe generates and receives sound waves using a principle called the piezoelectric (pressure electricity) effect. In the probe, there are one or more quartz crystals called piezoelectric crystals. When an electric current is applied to these crystals, they change shape rapidly. A piezoelectric crystal vibrates when an electric signal is applied, producing high frequency sound pressure waves, which we call ultrasound. This type of crystals can also work in reverse. It can produce electrical signals when it detects high frequency sound pressure waves. When a transducer directs ultrasound waves into the body, they pass right through the skin and into the internal anatomy. As the waves encounter tissues with different characteristics and densities, they produce echoes that reflect back to the piezoelectric crystal. This happens more than a thousand times a second. In addition all the crystals are repeatedly activated many times in such a way that a complete image frame is formed around 20 times per second. So that real time motion is displayed in the ultrasound image.
There are several types of transducer probes, each designed for specific applications. The most common types include:
1) Linear probe: These probes produce a high-resolution image and are commonly used for arteries, veins, skin, breast, vascular and musculoskeletal imaging. Their frequency is about 5-10 MHz and they have 9 cm depth.
2) Phased array probe: These probes are designed for cardiac imaging and we can see heart, lungs, abdomen, pleura and deeper structures in the body. Their frequency is about 1-5 MHz so we can get a higher penetration (35 cm depth) but lower resolution.
3) Curvilinear probe: These probes are use for viewing intra-abdominal structures such as kidney, liver, bladder, uterus etc. They uses low frequency about 2-5 MHz which allows them to have deeper penetration and about 30 cm depth of field.
* CPU: The computer that does all of the calculations and contains the electrical power supplies for itself and the transducer probe. Also we have transducer pulse controls that changes the amplitude, frequency and duration of the pulses emitted from the transducer probe.
* Display and keyboard: Display defined as screen to a surface and its function is to facilitate the projection of images in real time. It allows us to see what is happening inside the body at that moment. Keyboard inputs data and takes measurements from the display.