Ahmadi, F., McLoughlin, I. V., Chauhan, S., Ter-Haar, G. (2012) Bio-effects and safety of low-intensity, low-frequency ultrasonic exposure. PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY, 108 (3). pp. 119-138. ISSN 0079-6107

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Abstract

Low-frequency (LF) ultrasound (20-100 kHz) has a diverse set of industrial and medical applications. In fact, high power industrial applications of ultrasound mainly occupy this frequency range. This range is also used for various therapeutic medical applications including sonophoresis (ultrasonic transdermal drug delivery), dentistry, eye surgery, body contouring, the breaking of kidney stones and eliminating blood clots. While emerging LF applications such as ultrasonic drug delivery continue to be developed and undergo translation for human use, significant gaps exist in the coverage of safety standards for this frequency range. Accordingly, the need to understand the biological effects of LF ultrasound is becoming more important. This paper presents a broad overview of bio-effects and safety of LF ultrasound as an aid to minimize and control the risk of these effects. Its particular focus is at low intensities where bio-effects are initially observed. To generate a clear perspective of hazards in LF exposure, the mechanisms of bio-effects and the main differences in action at low and high frequencies are investigated and a survey of harmful effects of LF ultrasound at low intensities is presented. Mechanical and thermal indices are widely used in high frequency diagnostic applications as a means of indicating safety of ultrasonic exposure. The direct application of these indices at low frequencies needs careful investigation. In this work, using numerical simulations based on the mathematical and physical rationale behind the indices at high frequencies, it is observed that while thermal index (TI) can be used directly in the LF range, mechanical index (MI) seems to become less reliable at lower frequencies. Accordingly, an improved formulation for the MI is proposed for frequencies below 500 kHz. (c) 2012 Elsevier Ltd. All rights reserved.

Item Type:	Review Article
Authors (ICR Faculty only):	terHaar, Gail
All Authors:	Ahmadi, F., McLoughlin, I. V., Chauhan, S., Ter-Haar, G.
Additional Information:	ISI Document Delivery No.: 934DK Times Cited: 0 Cited Reference Count: 147 Ahmadi, Farzaneh McLoughlin, Ian V. Chauhan, Sunita ter-Haar, Gail Pergamon-elsevier science ltd Oxford
Uncontrolled Keywords:	Hazard Bio-effects Low-frequency ultrasound Sonophoresis Mechanical index Thermal index transdermal drug-delivery gas-body activation diagnostic ultrasound acoustic cavitation percutaneous-absorption therapeutic ultrasound inertial cavitation future-prospects in-vitro sonophoresis
Research teams:	ICR divisions > Radiotherapy and Imaging > Therapeutic Ultrasound
Depositing User:	Users 11 not found.
Date Deposited:	28 May 2012 11:04
Last Modified:	28 May 2012 11:04
URI:	http://publications.icr.ac.uk/id/eprint/11649

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