Ultrasound: Seeing with sound 

For her essay on the 'STEM of everyday life', runner up Elora Guirguis asks, how does ultrasound work?

Congratulations to Elora Guirguis, for being a runner-up in the 2021 UNSW Bragg Student Prize for Science Writing

In her response to the theme The STEM in Everyday Life, Mater Dei Catholic College student Elora Guirguis walks us through the way STEM is used in ultrasounds.

A delightful essay with a strong personal connection, exploring the wonder of everyday technology,” exclaims Bragg Prize judge and Careers with STEM co-founder Heather Catchpole. “I particularly applaud the personal connection of the writer to her topic, the imaginative quality of the writing, and the use of analogy to understand the technology.”

“Elora’s essay left all of us in awe of her ability to use richly poetic language to connect us as readers to this everyday technology that she and so many of us depend on for its life-saving ability to see into our bodies,” says award-winning Bragg Prize judge Ceridwen Dovey. “She is not only able to write beautifully about ultrasound but she is deft in describing the science behind how it work with wonderful metaphors and analogies (like bats seeing in the dark) and that lovely image of the crystals vibrating in order to make the magic of ultrasound work. She also folds in scientific references seamlessly, weaving an essay that stands out for its complexity and sophistication.”

Read Elora’s full essay below.

Ultrasound: Seeing with sound

It may be to see your child for the first time: an extension of oneself, a newfound meaning in life. Or it might be to confirm a diagnosis, with fingers crossed, heart pounding, and the whisper of prayers – regardless, the ultrasound is an essential piece of technology today. This medical test, also known as sonography, is constantly conducted every day around the world for all sorts of reasons. Yet, all too often, we forget the technology, the science behind these amazing machines. In the blurs of everyday life, when do you ever find yourself pondering how the everyday objects you use come to be?

Scaling down to my world, I have experienced the astounding work of ultrasound tests. In being diagnosed with an extremely rare health condition that affects 1 in around 13 700 newborns worldwide when I was born, I was at a significantly high risk of developing several forms of cancerous tumours. In particular, I was at a 20–30 per cent risk of obtaining a certain kidney cancer called Wilms tumour and liver cancer called hepatoblastoma up until the age of 10. I was to get an ultrasound every six months. Despite the fears and uncertainties and desperate prayers it brought along, I am ever grateful for the opportunity I had to check my health. If it were not so, I would have to live day by day, fearing for the unknown, for my future. 

To learn more about this wonderful machine, we must first know what it is and its origins. An ultrasound is a 20–60-minute-long medical test that uses sound waves to capture live images from within a person’s body non-invasively. With this, a doctor can investigate for a certain diagnosis or monitor a baby’s health. As made clear by the British Medical Ultrasound Society (BMUS), ultrasound was first introduced in medicine during and shortly after World War II – around 1956 – for clinical reasons.

You may be wondering, how on earth can one use sound and turn it into the sonogram images we see today? Think of it like this. In a pitch-black cave, it’s almost impossible to see. Bats, however, can navigate the rocky topography at high speeds, even with their eyes closed. This is because when bats fly, they use their ears rather than their eyes to create a map. Seeing with sound might seem nearly impossible, but just like bats, doctors do it all the time using the wondrous properties of ultrasound. 

The term ‘ultrasound’ refers to sound with a frequency, or number of cycles per second, that ranges from 2–10 million Hertz. That’s over 100 times higher than the human ear can hear! All sound is created when molecules in the air, water, or any other medium vibrate in a pulsing wave. Before the ultrasound begins, the inspected body part is covered with a conductive gel. This is because sound waves lose speed and clarity when travelling through the air; hence, as the National Institute of Biomedical Imaging has emphasised, we need an ‘airtight seal between the body and transducer’. Then, the heart of this wonderful system, or the transducer, is placed on the inspected body part and moved back and forth, commencing the process. A transducer is a little device that converts energy from one form to another. While this is happening, it begins rapidly sending ultrasound beams into the body using an array of piezoelectric crystals – crystals that vibrate when an electrical signal is applied. This is what forms our high-frequency pressure waves, or ultrasounds. 

The amazing thing about these crystals – they can also work in reverse! The waves pass right through the skin and all bodily liquids like blood, but as soon as they encounter a solid structure, they immediately bounce back to the piezoelectric crystal. This repeats thousands and thousands of times until each echo is rendered as a dot on the imaging screen, creating the detailed images and real-time motion we see today. All the different shapes and sizes we see on the screen are rendered according to different characteristics and densities of certain bodily parts. Dense objects, like bones, reflect the most waves, and hence appear as tightly packed dots and bright white shapes. Less dense objects, like heart valves, appear in fainter shades of grey. 

And voilà – a sonogram has formed! Using science, this valuable diagnostic tool can now help doctors observe infants and rule out or make a diagnosis in a safe, effective and fast way with no side effects. 

Without the wondrous works of ultrasound, I, like many others, would never make it through my health journey. Though it was tough, with scares and prayers and hope along the way, ultrasounds helped ensure I could lead a prosperous life despite my diagnosis.

For the 2021 UNSW Bragg Student Prize for Science Writing we asked Australian high school students to enter 800-word essays responding to the 2021 theme of The STEM in Everyday Life.

Read the other winning essays:

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Author: STEM Contributor

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