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What is an Ultrasound Probe and its types?

What is an Ultrasound Probe and its types?
June 14
13:19 2019

An Ultrasound probe, also known as Ultrasound transducer is a device that produces high energy sound waves by piezoelectric crystals which generate and receive sound waves. When these high energy sound waves bounce off the flesh or the body tissues, they produce echoes send to the computer, and the computer interprets these sound echoes into a picture called sonogram.

Transducers (Probes) come in different shapes and sizes in tandem with the picture size of different body parts or organs being investigated. Some ultrasound probes are passed over the body surface, whereas others are inserted into the body through the body openings like a vagina, for example, to inspect reproductive organs in women. They are referred to as internal transducers (probes) whereas those ultrasound probes used externally are known as external transducers (probes).

Types of Ultrasound Probes

There are three most common types of ultrasound transducers (probes), namely: convex, linear, and phased array. The difference is in their construction, piezoelectric crystal arrangement, aperture or footprint, and frequencies. I will list down the most common types of transducers (probes) although there exist more types in the market, I will delve deeper in the three most common types.

 The Convex Transducers (Probes)

The convex ultrasound transducer (probe), also known as a curved transducer has its piezoelectric crystal arrangement being curvy in nature. Its beams’ shape is convex, and it is suitable for in-depth examinations, its image resolution decreases with the increase in depth. The footprint, the frequency, and applications depend on whether the product is meant for 2 dimensions or 3 dimensions imaging. The convex transducer in 2 dimensions imaging is characterized by wide footprint product and the central frequency ranging between 2.5MHz and 7.5MHz. It is mainly used for abdominal, trans-vaginal, trans-rectal examinations and also for organ diagnosis. The convex transducer for 3 dimensions imaging, its central frequency range is between 3.5MHz and 6.5MHz. It has a wide field of view, and it is typically used for abdominal examinations.

The Phased Array Transducers (Probes)

The phased array transducers are named after the way their piezoelectric crystals are arranged. They have a small footprint and low central frequency of between 2MHz and &.5MHz. The beam point is narrower, but it has the ability to expand depending on the frequency applied. Their beam shape is triangular, and the near-field resolution is poor. It is mostly used in cardiac examinations; including trans-esophageal examinations, abdominal and brain examinations.

Linear Transducers (Probes)

In linear transducers, the piezoelectric crystal arrangement is linear, the beam shape is rectangular, and the near-field resolution is good. The footprint, the frequency, and application of transducers often depend on whether the product is 2D or 3D imaging. For 2D imaging, it has a wide footprint, and it’s center frequency is between 2.5MHz and 12MHz. This transducer has various applications including but not limited to; vascular examination, venipuncture blood vessel visualization, breast, thyroid, tendon, arthrogenous, intra-operative, laparoscopy, the thickness of the fats & muscular and locomotive syndrome and finally photoacoustic imaging. The linear transducers for 3D imaging have a wide footprint and a central frequency that ranges from 7.5MHz and 11MHz. It is generally used in breast, thyroid, and arterial carotids of vascular application.

Other Types of Ultrasound Probes

Pencil Transducers

This transducer is also called CW Doppler probes, and it is used for measuring blood flow and blood sounds. It comes with a small footprint with low central frequency, typically 2MHz to 8MHz.

Endo-cavitary Probes

These are ultrasound probes which allow internal examination of a patient; they are designed to fit into the human openings like rectum and vagina. They have small footprints, and their frequencies range from 3.5MHz and 11.5MHz.

Benefits of using Ultrasound

Ultrasound machines can produce high-quality images without emitting harmful radiations like x-ray, and the likes do, they are even safe on pregnant mothers. The ultrasound machines are portable and inexpensive nowadays; you can hardly miss finding one with a local doctor nearby. Therefore, doctors can examine the internal organs of their patients without having to refer them to the medical imaging centers in the cities. Finally, the ultrasound machines are easy to use as compared to MRI (Magnetic Resonance Imaging) and CT (Computer Tomography).

Repair of ultrasound probes

In some cases, repairs of ultrasound probes are inevitable, because the cost of probe repair is sometimes a small fraction of the actual cost. Therefore it is wise to repair them than to purchase a replacement. The most common repairs done to probes may include;

Strain Relief

This is a crack or the separation of the strain relief; it happens most often at transducer connector or where the probe attaches itself to the cable.

Image Dropout

Image dropout is denoted by black lines throughout the image. This happens when the piezoelectric crystals are not sending or receiving signals. This can only be fixed by replacement of the same device.

Worn, Cracked, or Holes in the Membrane

The membrane of the transducer wears out because of its extended usage over a period; this happens as normal wear and tear. Manufactures of transducers can only fix this problem. Broken Locking Mechanism This is a problem associated with the ultrasound connect when proper care is taken to connect or reconnect the transducers; the problem becomes minimal and can be solved easily.

Top Ultrasound Probe Brands

There are several brands of ultrasounds probes available today in the market. The following are some popular brands:

  • Acoustic
  • Acuson
  • Aloka
  • Apogee
  • ATL
  • Bio sound
  • BK
  • Butterfly
  • Chison
  • Diasonics
  • Esaote
  • FukudaDenshi
  • GE Ultrasound Probes
  • Hitachi
  • HP
  • Medison
  • Mind ray
  • Philips
  • Samsung
  • Siemens
  • SI UI
  • Sonoscape
  • Sonosite
  • Terason
  • ToshibaZonare

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