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The transient thermoelectric technique for measurement of the
absorption coefficient in biological materials was developed by
William Fry and colleagues in the Bioacoustics Research Laboratory
in the early 1950s. This technique continues to be the only technique
for directly measuring the absorption coefficient, as opposed to
the attenuation coefficient which includes effects of scattering
in addition to absorption, in inhomogeneous tissue samples. Over
the years since its development many measurements have been made
in this laboratory (see references below) and others using this
technique or modifications of it.
Very briefly the measurement technique uses very small diameter
thermocouples that are inserted into the tissue to measure the rate
of temperature rise as the tissue is sonicated with an ultrasound
beam of known intensity. Using the density and heat capacity of the
tissue and the depth of the thermocouple one can easily calculate
the absorption coefficient in the sample.
References
W. J. Fry and R. B. Fry. Determination of Absolute
Sound Levels and Acoustic Absorption Coefficients by Thermocouple
Probes - Theory. Journal of the Acoustical Society of America, 26,
294-310, 1954.
W. J. Fry and R. B. Fry. Determination of Absolute
Sound Levels and Acoustic Absorption Coefficients by Thermocouple
Probes - Experiment. Journal of the Acoustical Society of America,
26, 311-317, 1954.
D. W. Duback, L. A. Frizzell and W. D. O'Brien, Jr.
An Automated System for Measurement of Absorption Coefficients Using
the Transient Thermoelectric Technique. Proceedings of the 1979
Ultrasonic Symposium, pp. 388-391, 1979.
K. I. Bailey, W. D. O'Brien, Jr. and F. Dunn.
Ultrasonically Induced Temperature Elevation in Mouse Ovary.
Ultrasound in Medicine and Biology, 10, L492-L499, 1984.
S.A. Goss, J. W. Cobb, and L. A. Frizzell. Effect
of Beam Width and Thermocouple Size on the Measurement of Ultra-sonic
Absorption Using the Thermoelectric Technique. 1977 Ultrasonics
Symposium Proceedings, IEEE Cat. No. 77CH 1264-1SU, pp. 206-211, 1977.
S.A. Goss, L. A. Frizzell, and F. Dunn. Frequency
Dependence of Ultrasonic Absorption in Mammalian Testis. Journal of
the Acoustical Society of America, 63, 1226-1229, 1978.
S.A. Goss, L. A. Frizzell, and F. Dunn. Ultrasonic
Absorption and Attenuation in Mammalian Tissues. Ultrasound in
Medicine and Biology, 5, 181-186, 1979.
J.L. Drewniak, L. A. Frizzell, and F. Dunn. Errors
Result-ing from Finite Beam width and Sample Dimensions in the Determination
of the Ultrasonic Absorption Coeffi-cient. Journal of the Acoustical
Society of America, 88, 967-977, 1990.
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