16. Biological Effects of Ultrasound

  1. Charles A. Kelsey PhD,
  2. Philip H. Heintz PhD,
  3. Daniel J. Sandoval MS,
  4. Gregory D. Chambers MS,
  5. Natalie L. Adolphi PhD and
  6. Kimberly S. Paffett MS

Published Online: 3 JAN 2014

DOI: 10.1002/9781118517154.ch16

Radiation Biology of Medical Imaging

Radiation Biology of Medical Imaging

How to Cite

Kelsey, C. A., Heintz, P. H., Sandoval, D. J., Chambers, G. D., Adolphi, N. L. and Paffett, K. S. (eds) (2014) Biological Effects of Ultrasound, in Radiation Biology of Medical Imaging, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118517154.ch16

Editor Information

  1. Department of Radiology, University of New Mexico

Publication History

  1. Published Online: 3 JAN 2014
  2. Published Print: 24 JAN 2014

ISBN Information

Print ISBN: 9780470551776

Online ISBN: 9781118517154



  • Diagnostic radiology;
  • biology of diagnostic radiology;
  • ultrasound imaging;
  • biological effects of ultrasound;
  • ultrasound equipment


Ultrasound produces biological effects by two tissue interactions: heating and cavitation. This chapter discusses the properties and procedures of medical ultrasound and their clinical application, the two mechanisms and their potential biological effects. Ultrasound waves used in medical imaging have frequencies from 1 to 20 MHz; low-frequency sound waves penetrate deeper into tissue than high-frequency sound waves. A modern universal clinical ultrasound unit is usually portable so it can be taken directly into a patient's room. The unit displays two important safely parameters: thermal index (TI) and mechanical index (MI). The biological effects of ultrasound waves are directly related to the sound intensity and power. The Food and Drug Administration (FDA) limits the spatial peak-time average (SPTA) to 720 mW/cm2 because the cooling capacity of tissue is relatively high and most of the time in an ultrasound cycle is spent in the listening mode.