Similarities in the biological effects of laser light and ultrasound

Similarities in the biological effects of laser light and ultrasound

Bio-acoustics group meeting London, UK, 6 July 1979 The meeting opened with a paper by R.E. Apfel (Yale University) on using standing wave ultrasoni...

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Bio-acoustics group meeting London,

UK, 6 July 1979

The meeting opened with a paper by R.E. Apfel (Yale University) on using standing wave ultrasonic fields to separate red blood cells and other biomaterials. The equipment used frequencies of 300-600 kHz and 2-4 MHz and appears to have potential in separating components of equal density by their elastic properties. Among other papers presented was a talk by W.L. Nyborg (University of Vermont) on gaseous microbodies. These small bubbles are not stable as free entities but may be so when trapped in intercellular spaces. He showed a film of such bubbles trapped in a synthetic membrane used for fiitering. Significant changes in tissue can be noticed even at low ultrasonic intensities and it is clear that more research is needed into this subject. Evidence that a non-thermal effect of cell killing on heated cells is produced by ultrasound was presented by C. ter Haar (Institute of Cancer Research, Surrey). Suspensions of V79 cells had been irradiated with 3 W cm-*, 3 MHz con-

Similarities in the biological effects of laser light and ultrasound - Professor P. Greguss In our report on Ultrasonics International 79 (Ultrasonics 17 (1979) 281) we included a mention of Professor Greguss’ paper on accelerating the healing of ulcers. Professor Greguss has asked us to make clear that he does not

Handbook Edited

by

Kossoff,

of clinical ultrasound M.

A.

de

Vlieger,

Kratochwil,

J.H. R.

Holmes,

Kraus,

J.

E.

Kazner,

Poujol

and

G. D.E.

Strandness John Wiley

and Sons (1978)

xviii + 970

pp, f42.50

This massive volume contains more than 90 chapters, grouped into eight specialty areas, each edited by a leading authority in their field. The majority of the book deals, of course, with clinical aspects, with sections on: obstetrics/ gynaecology, internal medicine, cardiology, Doppler techniques, neurology, ophthalmology, and head and orthopaedics .

ULTRASONICS.

JULY

1980

tinuous ultrasound in the temperature range of 37”-45”C. At temperatures below 37” no cell killing was observed for up to 6 h irradiation. In the range 42”-45”C, however, cell killing was greater than that which could be attributed to heat alone. M. Dyson (Guy’s Hospital Medical School) described improvement in the mechanical properties of scar tissue following treatment with therapeutic levels of ultrasound. Rat tissue, having cryosurgical lesions, was found to be stronger with ultrasound as long as months after the irradiation. The effect of therapeutic ultrasound on the rate of fading of human bruises was reported by A.R. Williams (University of Manchester). Bruises produced by suction continue to develop and change colour for up to 3 h. Irradiation with ultrasound immediately after bruising resulted in a small increase in lividity. Bruise lividity was measured using fibre optics for up to 5 days, but no significant difference between the rate of fading of sonicated or untreated bruises was apparent.

assert that coherence is involved in healing with either ultrasound or lasers. Using polarized incoherent light, 80% of the effect with the laser can be achieved, while there is no effect when unpolarized incoherent light is used. The full paper has been published in the conference proceedings: Ultrasonics International 79, IPC Science and Technology Press, Guildford (1979) 301.

The first section, however, deals with basic principles, and is edited by G. Kossoff. Within this section the first chapter, written by P.N.T. Wells, gives a brief history of ultrasonics, and includes 106 references. The same author provides the next chapter, on basic physics, where the reader is briefly and clearly led from simple harmonic motion, through decibel notation and reflection and refraction, to the Doppler effect and absorption and attenuation. The transducer and principles and applications of greyscale echography are dealt with by Kossoff himself, and further chapters in the section are: pulse-echo techniques (C. Hellmuth Hertz), artifacts, and computer applications (D.E. Robinson), standardization (D.A. Carpenter), transducer arrays (J.C.

189

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