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How to pick the right transducer for your Diagnostic Ultrasound!

Choosing the correct ultrasound transducer is the key to maximising the performance of your ultrasound and keeping the cost down!

diagnostic ultrasound 3

Choosing the correct ultrasound transducer is the key to maximising the performance of your ultrasound and keeping the cost down!

In this blog post, we will explain the different transducer types available and hopefully give you more clarity on what types of examinations you can use them for, and ultimately, which ones you need!

First, let’s establish what an ultrasound transducer is and does?

An ultrasound transducer/probe is the key component of your ultrasound system. This is what sends out and receives the sound waves that bounce off body tissues. These sound waves are interpreted by the machine to give you an image aka a sonogram.

Ultrasound Transducer Types

When looking into this with varying companies, you will see transducers of all shapes and sizes. What also doesn’t help, is that they all have slightly different, coded names and it all gets a little confusing!

The reason you have such a range is that you need varying specifications across several parts of the body.

You have:

  • External transducers
    • Placed on the skin
  • Internal transducers
    • Inserted into a cavity e.g. rectum

Transducers also vary in:

  • Piezoelectric crystal arrangement
  • Aperture (footprint)
  • Frequency

What are these?

The piezoelectric crystal is the material inside the transducer that creates sound waves. The arrangement dictates the shape of the ultrasound beam and how the image is obtained and affects the footprint.

Aperture, known simply as the footprint, is the part of the probe that is in contact with the body. The footprint is linked to the arrangement of the piezoelectric crystals and comes in different shapes and sizes e.g. Linear/Convex

Frequency refers to the frequency of the sound waves produced from the transducer. Generally, higher frequencies offer better image quality at a superficial level whereas lower frequency is better for deeper structures.

As you know, Physiquipe specialise in MSK rehabilitation, but that doesn’t mean we can’t provide other Diagnostic Ultrasound configurations.

Below we list the transducer types and their applications. For MSK, the primary transducer types used are linear and convex. To find out more about the transducer range for Alpinion, visit the Alpinion product page here.

diagnostic ultrasound 4 transducer

Linear Transducers

The typical characteristics for the linear transducer are that the:

  • Piezoelectric crystal arrangement is straight
  • Resolution of the near field is good
  • Shape of the beam is rectangular

Let’s take the L3-12H from the Alpinion E-Cube 8 Diamond.

This transducer is a high-density transducer. Compared to the L3-12T, this means there is more crystal in the H which improves image clarity.

Linear transducers, particularly ones between 3-18MHz are considered good “all-round” transducers and are often the go-to transducer for MSK applications.

You can use linear transducers for various applications, including:

  • MSK indications
  • Vascular
  • Blood vessel visualisation
  • Breast
  • Small parts
  • Thyroid
  • Intraoperative, laparoscopy
  • The thickness measurement of body fat and muscular tissues.

Convex Transducers

The convex ultrasound transducer, aka the curved transducer, is called this due to the piezoelectric crystal arrangement being ‘curvilinear’.

This means the beam shape is much wider and is much better for examinations of deeper structures.

Convex transducers tend to have a wide footprint and a lower frequency of 1-8Hz.

You can use a convex transducer for examinations of:

  • Musculoskeletal
  • Abdominal
  • Vascular
  • Nerve
  • OB/GYN

There is a subtype called micro convex. This transducer has a much smaller footprint and typically used for neonatal and paediatrics applications.

Phased Array Transducers

A Phased Array transducer has a small footprint and low frequency with a narrow beam point that expands depending on the frequency applied.

The beam shape is almost triangular and with relatively poor near-field resolution.

A Phased Array transducer is typically used for:

  • Cardiac examinations, including
  • Abdominal examinations
  • Brain examinations

Pencil Transducers

You may hear these being called CW Doppler probes. These are used to measure blood flow and the speed of sound in blood.

This probe has a small footprint and uses low frequency (typically 2Mhz– 8Mhz).

Endocavity Transducers

These probes enable you to perform internal examinations and are specifically designed to fit in body orifices.

They tend to have small footprints and the frequency between 3Mhz – 12Mhz.

These are typically used for:

  • OB/GYN
  • Abdominal

Tips You Should Follow When Buying an Ultrasound Transducer

diagnostic ultrasound 5 transducer

Now, you are aware of the ultrasound transducer types, we have a few tips from our Clinical Advisory board on what you should follow when purchasing ultrasound transducers:

  • Triple-check that the probe you want is right for the applications you need it for
  • The lower the frequency, the deeper the sound penetrates – the catch is you lose some clarity
  • The higher the frequency the better this is for superficial scans, but is limited for anything past 6-8cm (depending on the frequency range available)

Things to know…

  • A black, vertical line on your image screen will most likely mean that the transducer has a dead crystal.
  • A shadow on the image screen may indicate a weak crystal inside the transducer that is not sending out enough sound.

If you experience either of these, speak to our servicing department for support.

 How Should You Treat Your Transducer?

The transducer is the most important, and very expensive part of an ultrasound system.

Therefore, you need to look after it. All Alpinion transducers come with a 2-year warranty as standard, but you should still use it carefully. Take note of the following:

  • Avoid dropping or knocking the transducer
  • Do not force the transducer into the port
  • Avoid damage to the duct of the transducer
  • Wipe the gel from the transducer after each use
  • Read the cleaning advice in the manual!

To learn more about servicing and maintenance, click this link to our blog covering this.

Otherwise, we hope that this information has made it a little clearer what transducer you may need…

If you have any more questions about transducers or any of Physiquipe’s Diagnostic Ultrasound solutions, contact us to speak to our team who are here to help and advise!

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