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ADVERSE BIOLOGICAL EFFECTS OF ULTRASOUND ON BODY TISSUES

First broadcast on www.provet.co.uk  

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Ultrasound is widely used in human and veterinary medicine as a diagnostic imaging technique, and also as a therapeutic technique. What adverse effects does ultrasound have on tissues ?

There are several known effects of ultrasound on tissues, but at the low doses used in diagnostic imaging these are not thought to create any adverse effect. At higher therapeutic doses the effects are used to influence tissues.

The various effects of ultrasound can be categorised into three main types :

  • Mechanical - no adverse effect on cell structure or chromosomes have been reported
    • Vibration of tissues 
      • Forms small cavities in fluids during "suction" phase which disperse during the "pressure" phase
      • This phenomenon is called cavitation in gas-free fluids, and pseudocavitation in fluids containing gas
    • Vibration associated with high intensities of ultrasound result in heat production
  • Heat 
    • At usual frequencies and intensities the heat produced by ultrasound is dispersed by the local blood circulation
    • High intensity ultrasound is used to induce local hyperthermia for therapeutic purposes
  • Chemical 
    • Depolymerisation - experimentally ultrasound can breakdown polysaccharides and polypeptides including DNA. These effects have not been reported to occur in vivo following diagnostic ultrasound procedures.
    • Oxidation
    • Reduction

High intensity, high frequency ultrasound has been shown to result in adverse effects including :

  • Tissue necrosis
  • Chromosomal damage
  • Genetic mutations
  • Teratogenic changes

So far these adverse effects have not been reported following diagnostic ultrasonography but safety limits to minimise potential risks have been set as follows :

  • Intensities over 100mW/cm2 (spatial peak/temporal average) should only be applied for a few seconds/minutes.
  • For human use 10 mW/cm2 is approved for commercial 2-D ultrasound.

 

Last updated : January 2016