1. The Physics of Ultrasound

  1. Ian Johnston1,
  2. William Harrop-Griffiths2 and
  3. Leslie Gemmell3
  1. Graham Arthurs

Published Online: 10 NOV 2011

DOI: 10.1002/9781118227978.ch1

AAGBI Core Topics in Anaesthesia

AAGBI Core Topics in Anaesthesia

How to Cite

Arthurs, G. (2011) The Physics of Ultrasound, in AAGBI Core Topics in Anaesthesia (eds I. Johnston, W. Harrop-Griffiths and L. Gemmell), Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781118227978.ch1

Editor Information

  1. 1

    Raigmore Hospital, Inverness, UK

  2. 2

    Imperial College Healthcare NHS Trust, London, UK

  3. 3

    Wrexham Maelor Hospital, Wrexham, UK

Author Information

  1. Wrexham Maelor Hospital, Wrexham, UK

Publication History

  1. Published Online: 10 NOV 2011
  2. Published Print: 29 NOV 2011

ISBN Information

Print ISBN: 9780470658628

Online ISBN: 9781118227978



  • physics of ultrasound;
  • ultrasound, acoustic energy;
  • obtaining best images;
  • clinical ultrasound devices;
  • complicated images, in real time;
  • pulsed ultrasound;
  • electrical charge, two-way;
  • transducer production;
  • speckle, spotty texture image;
  • ultrasound safety


• Ultrasound is a high-frequency pressure energy wave transmitted longitudinally through the soft tissues of the body.

• Advances in computer technology have made medical ultrasound possible by processing millions of signals every second.

• Ultrasound makes it possible to examine most of the tissues of the body safely and easily.

• The pressure, energy and heating effects of clinical ultrasound devices have not been shown to damage normal biological tissues.

• The ultrasound wave must be reflected off a tissue interface at right angles. This means that a combination of good hand–eye coordination and correct positioning of the probe is the basis of a good image.

• Images are presented as patterns on a greyscale monitor. Pattern recognition is therefore the basis of the interpretation of these images.

• The B or brightness mode gives a greyscale image that is distorted because of a loss of reflected echoes by scatter and refraction.

• Doppler shift is caused by a change in wavelength when fluid such as blood is moving towards or away from the ultrasound wave.