|University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
|Thursday, November 23rd, 2017|
Ultrasound Exposimetry Facility
A separate facility is maintained for precision calibration of the probes employed in the routine irradiation procedures as well as for the absolute determination of ultrasonic fields as laboratory standards. For the latter, radiation pressure on a rigid sphere provides an accuracy of +3 percent in absolute sound pressure level.
For the measurement of the acoustic pressure waveform for calibration of pulsed sources, the Bioacoustics Research Laboratory has a computer controlled automated scanning and data acquisition system. It is capable of supporting a 15 pound load and provides motorized movement (under manual or computer control) along three orthogonal linear axes (1 µm resolution) and rotation (0.01 degree resolution) about two axes (the vertical axis and one horizontal axis). The scanning system is controlled via an IEEE 488 interface by a System Controller (Intel 80386 based personal computer).
The personal computer is also used to control the data acquisition using a Textronix 11401, 500 MHz programmable digitizing oscilloscope. Several calibrated membrane and needle type PVDF hydrophone and PZT spherical probes are available for use in this system within the frequency range 1 kHz - 15 MHz. Using these probes and the digitizing oscilloscope, the pulse from an ultrasound laboratory transducer or diagnostic ultrasound system can be recorded and characterized as per the AIUM approved output labeling standard. Software is available for determining the frequency content of the pulse as well. Hydrophones which have been calibrated by the National Physical Laboratory, England or the Naval Research Laboratory, Orlando have been recalibrated in the Bioacoustics Research Laboratory and found to agree within 2% with field measurements made using the suspended steel ball radiometer. The system also has a dedicated SUN SPARCstation for image processing, employed to generate high quality graphs and two and three dimensional field plots.
For more information on the ultrasound exposimetry facility:
R. C. Preston, D. R. Bacon, S. S. Corbett III, G. R. Harris, P. A. Lewin, J. A. MacGregor, W. D. O'Brien, Jr. and T. L. Szabo. Interlaboratory Comparison of Hydrophone Calibrations. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 35, 206-213, 1988.
N. B. Smith, C. V. Vorhees, R. A. Meyer and W. D. O'Brien, Jr. An Automated Ultrasonic Exposure System to Assess the Effects of In Utero Diagnostic Ultrasound. Proceedings of the 1990 IEEE Ultrasonics Symposium, pp. 1385-1388, 1990.
J. A. Jensen, D. R. Gandhi and W. D. O'Brien, Jr. Ultrasound Fields in an Attenuating Medium. Proceedings of the 1993 IEEE Ultrasonics Symposium, pp 943-946, 1993.
A. Goldstein, D. R. Gandhi and W. D. O'Brien, Jr. Diffraction Phenomena with Co-Axial Plane Piston Transducers. Proceedings of the 1994 IEEE Ultrasonics Symposium, pp 1757-1760,1994.
N. B. Smith, A. G. Webb, D. S. Ellis, L. J. Wilmes and W. D. O'Brien, Jr. Non-Invasive In Vivo Temperature Mapping of Ultrasound Heating using Magnetic Resonance Techniques. Proceedings of the 1994 IEEE Ultrasonics Symposium, pp 1829-1832, 1994.
N. B. Smith, A. G. Webb, D. S. Ellis, L. J. Wilmes and W. D. O'Brien, Jr. Experimental Verification of Theoretical In Vivo Ultrasound Heating using Cobalt Detected Magnetic Resonance. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 42, 489-491, 1995.
A. G. Webb, N. B. Smith, D. S. Ellis and W. D. O'Brien, Jr. Non-Invasive In Vivo Temperature Mapping of Ultrasound Heating Using Fluorine-Based Magnetic Resonance Imaging Agents. Proceedings of the 1995 IEEE Ultrasonics Symposium, pp 1609-1612, 1995.
D. Swiney and W. D. O'Brien, Jr. Human Fetal Diagnostic Ultrasound Exposimetry System. Proceedings of the 1996 IEEE Ultrasonics Symposium, pp 1167-1169, 1996.
A. Goldstein, D. R. Gandhi and W. D. O'Brien, Jr. Diffraction Effects in Hydrophone Measurements. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 45, 972-979, 1998.
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|Bioacoustics Research Lab.|