The concept of ultrasound has been understood for much longer than you might think. As far back as the eighteenth century, Italian scientist Lazzaro Spallanzani noticed that bats navigate by sound rather than sight¹. The way bats interpret sounds to work out the shape and direction of objects is known as echolocation, and forms the basis of ultrasound technology.
Ultrasound uses sound waves that are too high for human hearing, but create echoes that bounce off objects². Just as a bat’s brain uses echoes as data to work out the sizes and shapes of objects around it, ultrasound technology can use echoes to “see” the inside of the body. A scanner combines the data from all the echo waves to build up a picture, known as a sonogram.
Ultrasound technology in healthcare is incredibly useful because it gives us images of the inside of the body without having to use radiation. Diagnostic ultrasound tools have been used in medicine since WW2.
Turning signals into sound
The tools that produce the sound waves for diagnostic ultrasounds are known as probes, or transducers. Ultrasound probes contain crystals with piezoelectric properties - that is, when electricity is applied, the crystal converts these electrical signals into sound waves which flow through the body³.
Crucially, this also works in reverse. When the crystal receives the sound waves from the echoes, it converts them into electrical signals. These signals are what the scanner uses to create the sonogram.
Types of ultrasound probes
Linear probes offer high-resolution images and are suitable for areas of the body that are small or close to the surface (like the thyroid).
Convex probes, or curvilinear probes, are good for in-depth scans. The lower-frequency kind is used for 2D imaging and the higher-frequency probes with a wide field of view are used for 3D imaging tasks such as abdominal examinations⁴.
Phased array probes have a lower number of crystals which fire in phases (hence the name)⁵. They are optimised for heart scans because they penetrate well under the skin and have a high “frame rate” for capturing moving structures.
Endocavity probes are designed to fit inside body orifices, so they have a small footprint. Their frequency is in the middle range, 3Hhz-10MHz.
Advancements in ultrasound probe technology
Traditional ultrasound scanning is 2D, meaning the ultrasound waves are sent and received on one plane. 3D scanning is possible because the technology now allows us to capture sound waves that are at slightly different angles to each other. The real advancement here is the computer software that can turn this information into a three-dimensional image. 4D scanning takes the technology to yet another level by producing a live video of the body.
The importance of disinfection
Ultrasound probes are a vitally important diagnostic tool in many areas of medicine, from cancer to gynaecology. These expensive and specialist medical imaging devices are used over and over again, which means it is vital to have an effective disinfection solution to reduce any risk to patients. It is also important that they are not out of action for too long.
UV-C disinfection uses the proven technology of UV-C light to destroy microorganisms, such as viruses and bacteria. The D45 is UV-Smart’s specialist solution for ultrasound probes - a compact device with fast-acting results. The entire disinfection process takes just 75 seconds⁷.
Ultrasound technology has moved forwards a lot in recent decades, from blurry black and white images to high-definition colour videos. It is important that disinfection technology moves on too, so we can get the most out of these important diagnostic tools.
References
¹ Return to the Magic Well: Echolocation Behavior of Bats and Responses of Insect Prey (American Institute of Biological Sciences, July 2001)
² NHS website guidance on ultrasound scans (July 2021)
³ What is the Piezeoelectric Effect? Nanomotion.com
⁴ Ultrasound Transducer Types and How to Select the Right Transducer, LBN Medical
⁵ Ultrasound Probes| The Break Down, Probo Medical (March 2019)
⁶ Ultrasound 101 - Part 1: Transducers 123 Sonography (January 2022)
⁷ UV Smart D45 Protocol, video from UV Smart (November 2023)
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