New Processing Techniques in Ultrasound Imaging Systems
Novel techniques are described that allow echo signals from ultrasound imaging systems to be processed at a reduced bandwidth. The basic principle consists in processing the complex envelope of the signal, independently of the carrier frequency. However, rather than at baseband, requiring phase-quadrature channels, processing is performed at i.f. by a single channel.
Even though various techniques are possible, surface-acoustic wave (SAW) transversal structures have been employed for the first time in a number of real-time processors.
Programmable delay-lines are described, exhibiting more than 50 dB dynamic range. Based on independent processing of echo carrier and envelope, a phased-array configuration requiring one single delay-line for all the array channels is introduced.
An Hilbert transformer allowing the exact echo envelope to be obtained is demonstrated, and the design of a real-time programmable inverse filter is described.
KeywordsDelay Line Quantisation Step Hilbert Transformer Pulse Envelope Inverse Filter
Unable to display preview. Download preview PDF.
- 2.O.T. Ramm, and F.L. Thurstone, Cardiac imaging using a phased array ultrasound system, Circulation, LIII; 258 (1976).Google Scholar
- 3.R.E. McKeighen, and M.P. Buchin, New techniques for dinamfcally variable electronic delays for real time ultrasonic imaging, in “Proc. IEEE Ultrasonics Symposium”, Cat 77CH 1264–1 SU: 250 (1977)Google Scholar
- 4.G. Manes, S. Gasperini, and C. Atzeni, A novel variable delay system for ultrasound beam steering/focusing, in “Septième colloque sur le traitement du signal et ses applications”, Nice, 103 /1 (1979).Google Scholar
- 6.G. Manes, C. Atzeni, and S. Gasperini, A single-channel reduced-bandwidth SAW-based processor for ultrasound imaging, in “Proc. IEEE ltrasonics Symposium”, Cat 79CH 1482–9 SU: 179 (1979).Google Scholar
- 7.C. Susini, Focalisation properties of a phased-array ultrasound imaging system based on a new type of delay compensation, Atti della Fondazione G.Ronchi, 3: 335 (1980).Google Scholar
- 8.“Surface Wave Filters”, H. Matthews, ed., J. Wiley & Sons, New York (1977).Google Scholar
- 9.G. Manes, and C. Atzeni, Baseband compatible SAW processors, Electron. Lett., 15: 661 (1979).Google Scholar
- 10.G. Manes, et al., Baseband compatible SAW processors: preliminary experiments, in “Proc. IEEE Ultrasonics Symposium”, Cat 79CH 1482–9 SU: 748 (1979).Google Scholar
- 11.“Application guide to CMOS multiplying D/A converters”, D.H. Sheingold, ed., Analog Devices, Inc. (1978).Google Scholar
- 12.A.V. Oppenheim, and R.W. Shafer, in “Digital signal processing,” Prentice Hall, Englewood Cliffs, New Jersey (1975).Google Scholar
- 13.D. Behar, et al., Use of a programmable filter for inverse filtering, Electron. Lett., 16: 88 (1980).Google Scholar
- 14.J.M. McCool, and B. Widrow, Principles and applications of adaptive filters, IEE Conf. Publ. 144: 84 (1976).Google Scholar