# Ultrasound

Did you know that our ears can only hear a limited range of sound frequencies? It's true! Some sounds are too high or too low for us to detect. For instance, have you ever heard of dog whistles? They make a sound that only dogs can hear because their ears are more sensitive to higher frequency sound waves. These waves are called ultrasound and they have a higher frequency than what we can hear.

## Ultrasound definition

Ultrasound is a type of sound that is too high-pitched for humans to hear. It has a frequency above 20 kHz, which is higher than what we can hear. Most people can hear sounds between 20Hz and 20 kHz, but we are particularly sensitive to frequencies between 2000 Hz and 5000 Hz. Even though we can't hear ultrasound, it has many useful applications. For example, fishing boats use sonar equipment that emits ultrasound waves to find the position of fish beneath them. The time it takes for the waves to reflect back can be used to determine the depth of the water. If the waves are directed at a shoal of fish, the fishermen can see how far away they are and catch them more easily.

Let's say a fishing boat is travelling in the Atlantic ocean and wants to know the depth of the water. They send ultrasound waves towards the seabed and get a peak in the electrical signal in the detector 12 seconds later. Using the equation s = v t, where s is distance, v is speed, and t is time, we can calculate that the distance travelled is 18000 m. However, since the waves have to travel to the seabed and back up to the boat, we need to divide the distance by 2 to get the depth of the ocean, which is 9000 m.

### Ultrasound scans

Ultrasound can also be used for foetal scanning - also known as pre-natal scanning. It enables doctors to check the sex of the babies before they are born. It can also be used to see if a baby is in good health and to find what position it is in.

When a mother undergoes a foetal scan, a probe is moved over her stomach, emitting ultrasound waves into her body. These waves get partially reflected whenever they reach a boundary between two different materials. As a result, some of the ultrasound signal will be sent back when it reaches the baby's body, which is a different material to the fluid surrounding it. The returning ultrasound radiation is then detected by the probe. By moving the probe around and measuring how long it takes for the ultrasound to return at different points, an image of the baby can be produced. This is possible because the known speed of the waves in the fluid can be used to calculate the distance travelled by the ultrasound waves.

Ultrasound has many other applications besides foetal scanning. It is commonly used in medicine to diagnose and monitor various conditions. For example, ultrasound can be used to examine the heart, liver, and kidneys, and to detect problems such as blood clots or tumours. It is also used in physiotherapy to promote healing and reduce pain in injured tissues. Additionally, industrial and engineering applications use ultrasound to detect flaws in materials and to measure distance and thickness. Overall, ultrasound is a valuable tool in many different fields.

### Other medical applications

While ultrasound is commonly associated with foetal scanning, it is also widely used for medical imaging in patients who have internal organ problems, such as damaged lungs or kidneys. Unlike X-rays, which use ionizing radiation and pose a potential risk of damage to internal organs, ultrasound is considered a safer alternative for medical imaging.

Ultrasound waves are emitted from a probe and penetrate the body tissues. As the waves encounter different tissue densities, some of the waves are reflected back to the probe, while others pass through to deeper tissues. The returning waves are detected by the probe and transformed into an image by a computer, which can then be used by doctors to diagnose and monitor various conditions.

In addition to being non-invasive and safe, ultrasound has other advantages as well. It is relatively inexpensive compared to other imaging techniques, and it can be performed quickly and easily, often without the need for a hospital stay. Furthermore, ultrasound can be used to guide minimally invasive procedures, such as biopsies and needle aspirations, which can reduce the risk of complications and speed up recovery times.

Overall, ultrasound is a valuable tool for medical imaging and has a wide range of applications in the diagnosis and management of various health conditions.

### Quality control

Ultrasound technology is not limited to medical and healthcare applications, as it is also widely used in industry to detect irregularities in materials, such as metal castings or pipes. This is accomplished by sending ultrasound pulses through the object and measuring the time it takes for the waves to travel through the material and reflect back to the probe. If the waves encounter a crack or flaw in the material, they will be partially reflected, creating a small pulse in the electrical signal detected by the probe.

By analyzing the time delay between the original pulse and the reflected pulse, engineers can determine the location and severity of the irregularity. This information can be used to identify potential defects or weaknesses in the material, allowing for repairs or replacements to be made before a catastrophic failure occurs.

Ultrasound equipment can be used to detect cracks in pipes, which can be a major problem in industries such as oil and gas or chemical processing. By using ultrasound technology, engineers can quickly and accurately locate cracks, corrosion, or other defects in pipes, allowing for timely repairs and preventing costly shutdowns or accidents.

Overall, ultrasound technology is a valuable tool for quality control and defect detection in various industries, helping to ensure the safety and reliability of structures and materials.

### Other medical applications

Ultrasound is not just used for people having babies, it can also be used for medical imaging purposes. For example, people who who are having some kind of problem with their internal organs, such as damaged lungs or kidneys.

You may have already learned about how X-rays can be used to identify internal problems with the body. There is much less risk of damage to your internal organs when using ultrasound as opposed to X-rays.

Ultrasound advantages Ultrasound is used in medicine for a variety of different medical problems. This is because it has some key advantages over other medical techniques: Ultrasound can be used to form images of internal organs without the need to operate on patients. This can save a lot of time and money in and prevents the risks associated with invasive surgery. The equipment used for ultrasound is inexpensive compared to other types of medical imaging equipment. It is also quite easy to transport and to operate. As mentioned above, ultrasound is not very harmful to internal organs (or for foetuses when it is used for foetal scanning). It does not cause any harm to the tissue in comparison with other techniques that require the patient to be exposed to ionising radiation such as X-rays which can sometimes be very damaging to cells in the body. Ultrasound can be used to capture images of soft tissues which will not show up when using other medical imaging techniques such as X-rays. This is because the pictures produced come from how ultrasound is partially reflected at the boundaries between materials and even if the electrical signal produced is small, the boundary can still be identified. On the other hand, X-rays work on the basis of forming a picture by passing X-ray radiation through the body and forming an image from the points where no radiation passes through (for example if it is blocked by a bone), so soft tissues will not be identified.

Ultrasound - Key takeaways Ultrasound is sound with a frequency above 20 kHz - this is the upper limit of the range of sound frequencies that humans can hear. Ultrasound is very useful in finding where objects and surfaces are that cannot be easily reached or cannot be measured directly. Images of babies can be made by the use of ultrasound foetal scanning. This involves directing ultrasound waves at the foetus and using the intensity of reflected waves at different points to form an image. There are many advantages of using ultrasound rather than other medical techniques as the equipment of cheaper, operations are not needed and ultrasound is much safer than many other methods.

## Ultrasound

### What is ultrasound?

Ultrasound is sound with frequency above the human hearing range.

### What is ultrasound used for?

Ultrasound has many applications, such as locating the position of fish below a fishing boat and also foetal scanning.

### What are the advantages of ultrasound?

Ultrasound equipment is inexpensive and ultrasound is not dangerous to human tissue.

### What are the advantages of ultrasound?

The advantages of ultrasound are varied. One of the main advantages of ultrasound is that it can be used for non-invasive medical imaging. It can also be used to visualise objects on the other side of physical barriers such as thick walls. Ultrasound has a number of properties that mean that it is useful for probing materials and gaining useful information from them by studying the reflected signals.

### What types of ultrasounds are there?

Ultrasound refers to acoustic waves that cannot be heard by humans. Therefore there aren't really many distinctions to make between different ultrasound except perhaps their sources and their particular frequencies. In medical imaging, however, different names are given to the various uses of ultrasound.