What Is Ultrasound Therapy

  • Isla Cogle BSc Immunology student, University of Glasgow
  • Reem Alamin Hassan Bachelor's degree, Biomedical Sciences, Queen Mary University of London, UK

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Ultrasound, a versatile medical technique rooted in the innovative use of sound waves, has evolved to become a cornerstone in both diagnostic and therapeutic areas of treatment. Here we will explain the mechanism of ultrasound therapy, its history, and the diverse applications that have emerged in the medical field. From its inception to its present-day advancements, the journey of ultrasound therapy unfolds through a lens that encompasses both diagnostic precision and therapeutic efficacy. 


Ultrasound therapy overview

Ultrasound therapy - sometimes referred to as ultrasonography - is a medical technique that is used both in therapy and diagnostic medicine. It uses ultrasound waves which can penetrate deep into the body to treat a wide variety of conditions, such as cancer, bone fractures, and kidney stones, among many others. It is a fast-developing field, with many new uses for this therapy being discovered which is allowing it to often replace surgery for minor procedures and for those for whom undergoing surgery is too risky. This is a result of limited side effects and no need for anaesthesia.

History of ultrasound therapy 

The idea for using ultrasound waves for treatment was first considered during the Second World War, as the ultrasonic mechanisms used to track submarines were found to heat up and kill fish. This led to the development of ultrasound therapy in the late 1940s.1 Low-power ultrasound became popularised in the 1950s, and in the 1980s became widely applied for use in lithotripsy, the process of breaking down kidney stones while still in the body which allows them to pass easier.2 

Differences between therapeutic and diagnostic ultrasound3

When used as a diagnostic tool, ultrasound aims to get a clear image of what is going on inside the body without having any type of lasting effect on the cells being pictured. It works by creating images of the internal bodily structures by sending in sound waves and recording the echoes which bounce back.

When used in therapy, the ultrasound waves are more focused and intense, to help to heal tissues or kill dangerous and damaged cells, depending on the type of ultrasound used. Low intensities can provide deep heating to tissues, promote circulation, and aid in the healing process of injuries, while higher intensities are used for ablative purposes, destroying tumours or tissues in a targeted manner. 

Types of ultrasound therapy


Thermal ultrasound therapy causes the vibration of tissues to heat the cells. This is most often used in soft tissue disorders and other muscular issues but can be used in the treatment of more advanced issues such as cancer. 

The heat of tissues can reduce swelling, muscle pain, and chronic inflammation when used at low levels, and at high levels can completely kill off dangerous or cancerous cells. In this case, targeted cells are heated to upwards of 60 degrees Celsius, which when lasting more than 1 second, induces a type of programmed cell death called apoptosis, in which the cell will kill itself due to the damage.2 


Mechanical ultrasound therapy is also known as cavitation ultrasound therapy, and during this, the waves cause pressure differences in the fluids present in the affected tissues. This creates bubbles in the fluids which burst when they interact with solid objects, leading to the formation of shockwaves. This can be used for many health issues and is commonly used in the lithotripsy treatment of kidney stones.  

High-intensity focused ultrasound2

High-intensity focused ultrasound (HIFU) is a common type of ultrasound therapy which heats cells to a level that kills them very quickly, called cytotoxicity, so it can effectively kill cancerous tumours without impacting the surrounding tissue. It is similar to conventional ultrasound in its clinical applications and mechanisms of action but produces waves at a higher intensity to perform precise therapies. 

As well as using thermal energy, HIFU uses mechanical effects including cavitation, which leads to high pressures and temperatures in the affected tissues. This creates jets of fluids that can be used to damage the walls of cells and kill them. A sharp line divides the dead and live cells due to the precise nature of HIFU. 

There are three ways HIFU therapy can be applied to the body:

  • For easily accessible areas, such as the kidney, ultrasound waves can be produced by an external transducer. This means the ultrasound wand stays outside the body and sends waves through an acoustic window on the skin (the area of the body where it is easiest to reach the affected tissue without interfering with healthy areas).
  • For cases such as prostate cancer, the waves are produced by a transrectal transducer where the wand is inserted into the body.
  • A new method being developed for cases such as oesophagal and biliary ductal tumours involves the probe being inserted through the mouth and threaded along until it reaches the site of the tumour.

Internal probes are usually set to a higher frequency and lower power than external transducers, as they have less space to travel through before reaching the target. The higher the frequency, the less tissue the waves will be able to travel through, so lower frequencies are required for external probes so they can pass through the skin and tissues effectively. 

Blood vessels have been shown to be less susceptible to damage from HIFU therapy than tumour cells, which makes this therapy a generally safe and effective alternative for surgery. However, if blood vessels are damaged, this can lead to deadly complications, so it may not be an appropriate technique if the affected area is close to any major blood vessels. 

Clinical applications

Malignant tumors2  

Ultrasound therapy has been successfully used in the treatment of many different types of cancerous tumours. These include tumours in the following: 

  • Liver – particularly hepatocellular carcinoma which is one of the most common and hardest to treat liver cancers
  • Breast – this is particularly useful in terms of breast conservation and allows the patient to avoid (breast surgery) 
  • Prostate  
  • Kidney – useful in the case of small renal tumours which are non-invasive 
  • Oesophagus  
  • Pancreas 
  • Brain  
  • Bone  

Other disorders6

While ultrasound therapy has been used effectively to treat many different types of cancer, its use doesn’t end there. A huge number of benign tumours and non-cancerous disorders have been treated with this therapy. This includes the following: 

  • Uterine fibroids 
  • Benign breast lesions 
  • Parkinson’s disease/essential tremor 
  • Chronic pain  
  • Cataracts 
  • Brain disorders 

Drug delivery3

Ultrasound therapy has also been shown to increase the efficacy of certain medications as the bubbles produced during cavitation in mechanical therapy can aid the movement of drugs in the body. Small quantities of drugs can be contained within the bubbles, which can circulate to target tissues. Ultrasound waves can destroy the bubbles, releasing the drug exactly where it is needed. 

Advantages of ultrasound therapy2

There is a long list of advantages of therapeutic ultrasound that makes it an attractive alternative to surgery in many cases. 

The main advantage is ultrasound’s ability to deliver precise energy to a target area in the body, without affecting the surrounding tissue. 

It is minimally invasive, as the skin does not need to be cut open to access the affected area. This means there is less risk of infection, reduced recovery time, minimal pain associated with the procedure, and generally no scarring left on the patient. There is also no requirement for anaesthesia, which makes it accessible for patients who are deemed too high risk for anaesthesia.

Compared to other ablation techniques, it is much less toxic and has fewer associated side effects, and the use of MRI or diagnostic ultrasound means the patient is not exposed to radiation associated with X-ray guidance. This also means that undisturbed visualisation can be used in the procedure, ensuring its accuracy and efficacy in real-time. 

As well as this, it is a low-cost form of treatment, both for the patient/provider and in terms of the maintenance and upkeep of the ultrasound machine, especially when compared to more complicated forms of treatment.  

Side effects and limitations2

While ultrasound therapy is relatively low risk with minimal side effects compared to other procedures, there are still some limitations that must be considered. These usually differ depending on the reason for therapy.

  • The main issue with ultrasound therapy is its ability to cause superficial burns on the surface of the skin. These are usually not severe, as caution is taken to ensure that the wand is not too hot and is being moved to avoid prolonged contact, although this can still occur. This causes pain and discomfort, and treatment has to be stopped for the skin to heal. During treatment for kidney stones, severe, second-degree burns have been reported. One advantage of HIFU is the fact that MRI can track the temperature in real time to help prevent burns.7
  • Other unpleasant side effects include pain in the targeted area and vomiting.  
  • There have been rare cases reported of vasospasm (narrowing of the arteries, restricting blood flow) and haemorrhaging (loss of blood due to damage to a blood vessel) if cavitation occurs in the tissue. Many cases of bleeding during the procedure can be managed by the ultrasound itself, though may need surgery to correct.  
  • In ultrasound treatment of liver and pancreatic cancer, the formation of fistulas (an abnormal connection between body parts) and rib necrosis are seen as serious associated complications. 
  • Some other considerations for ultrasound therapy include the long treatment time, as appointment times can take up to several hours, and the sensitivity of treatment to patient movement. As this is extremely targeted therapy, the patient must be still for the duration to ensure the ultrasound waves are targeting the right area of the body. 


  • Ultrasound therapy is quickly replacing surgery as a key treatment option for many different conditions  
  • It can be used for gentle heating to help with the healing of injuries and soft tissue issues, or for at higher intensity waves alongside mechanical effects it kills specific cells and tissues, which is useful for the treatment of cancer.  
  • It is non-invasive and has much fewer associated side effects than surgery, however, there are still issues which should be discussed with a medical professional before undergoing this type of treatment. 


  1. Izadifar Z, Izadifar Z, Chapman D, Babyn P. An Introduction to High Intensity Focused Ultrasound: Systematic Review on Principles, Devices, and Clinical Applications. Journal of Clinical Medicine [Internet]. 2020 Feb 7;9(2). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7073974/
  2. Miller DL, Smith NB, Bailey MR, Czarnota GJ, Hynynen K, Makin IRS. Overview of Therapeutic Ultrasound Applications and Safety Considerations. Journal of Ultrasound in Medicine [Internet]. 2012 Apr;31(4):623–34. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3810427/
  3. ter Haar G. Therapeutic applications of ultrasound. Progress in Biophysics and Molecular Biology. 2007 Jan;93(1-3):111–29.
  4. Morishita K, Karasuno H, Yokoi Y, Morozumi K, Ogihara H, Ito T, et al. Effects of Therapeutic Ultrasound on Range of Motion and Stretch Pain. Journal of Physical Therapy Science [Internet]. 2014;26(5):711–5. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4047237/
  5. Dalecki D. Mechanical Bioeffects of Ultrasound. Annual Review of Biomedical Engineering. 2004 Aug 15;6(1):229–48.
  6. de Lucas B, Pérez LM, Bernal A, Gálvez BG. Ultrasound Therapy: Experiences and Perspectives for Regenerative Medicine. Genes. 2020 Sep 17;11(9):1086.
  7. Matthews MJ, Stretanski MF. Ultrasound Therapy [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK547717/

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Isla Cogle

BSc Immunology student, University of Glasgow

Isla is an immunology student passionate about making science accessible to everyone. With years of experience as a science tutor and volunteer, she simplifies complex concepts and connects the public to current issues in medicine. Her dedication to education and medical communication drives her efforts to bridge the gap between research and public understanding, helping others to make informed decisions about their own health.

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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