- Email: [email protected]
Fourth ultrasound in biology and medicine symposium
(Guy’s Hospital, London). He and his colleagues have developed an integrated Doppler diagnostic system based on a new real-time frequency spectrum analyser and continuous wave vessel visualization system. The two most important areas of clinical application presently are in the initial assessment of multilevel occlusions in leg artei-ies, and in the haemodynamic conditions in the external vessels in the neck. Both as a method of patient management and as a guide to the need for X-ray angiography, the techniques are high.ly cost-effective. Finally, L. Angelini (Universita degli Studi di Roma, Rome) gave an illuminating talk on the role of ultrasound in preventive medicine. By preventive medicine, Professor
Angelini explained that he was referring to health surveillance. Stressing the apparent safety of diagnostic ultrasonic procedures, and their relatively low costs. hc explained that ultrasonic screening of individual patients presenting at llis clinic with particular clinical problems had revealed a significant number of unsuspected abn~~rlnalities. Thus. in the 2.500 diagnostic ultrasonic examinations carried out in his unit in 1978. unsuspected lesions had been discovet-ed in the liver, gaIl-bladder, bile ducts, pancreas, spleen, abdominal aorta. kidneys, bladder, prostate and uterus. The additional examination time required to ‘screen‘ these organs in each patient is only about 10 minutes. P. N. T. Wells
Fourth ultrasound in biology and medicine symposium Visegrad, Hungary, 25-28
September
1979
This fourth ultrasound in biology and medicine symposium under the auspices of the Hungarian Biophysical Society and the Applied Biophysics Laboratory of the Technical University Budapest had an attendance of nearly 90 from 13 different countries. The meeting embraced four sessions. each of which was introduced by an invited speaker, who gave a tutorial-critical review of the session’s main topic, including the papers published in Volume I of the Sytnposium Proceedings. Since this volume was distributed before the opening of the Symposium, each author of the reviewed paper had only 5 min to round off his paper by presenting new data. showing slides or figures not included in the Proceedings, etc, so there was more time for discussion than is usually the case in such meetings. In the intrL)du~t~)ry lecture P. Greguss (Hungary) comnlcmoi-ated the 30th anniversary of the Italian abbot L.a/./arc~ Spalanzani. who first demonstrated experimentally that bat5 may use sound waves for (~rieil~arion and target recognition. In this talk, the question was raised whether what had been learned since Spalanzani about echolocating animals could be used to improve uitrasonic diagnostics and intluence the design philosophy of these instruments. The was definitely positive. answer, although controversial.
and Sl1.D. Kakichashvili (LJSSR) described a new holographic technique which allows the visualization of the holographic irif~~rllla~~~~nwithout using an acoustic reference wave. The technique is based on the diffraction of light on the disturbed interface of two media. Although the description of the tecllnique was not discussed in detail, the re~~~nstrllcte(l images showed higher quality than the reconstru~tecl images WCal-e accustomed to see from conventional acoustical holographiz ~Il?aging techniques. Session II. the review papet- c)t‘wtiicll was read h?/ R. Millnci (GDR) was devoted to ultrasonic hi~mef 1-y :ttld tissue signature. MMOSI of the post-deadline papel-s were pt-esentc~l in this session. Discussions in this session wcrt’ merely 01 clinical nature rather tlian technical or physical.
Oiity two post-deadline
papers ark-ivccl to these t\st~ \iGtklt\.
The introductory paper on ultrasonic techniques for the investigation of carotid and vertebl-al artery diseases hy 13.N. White (Canada) was a good basis for those post-deadline papers that were dealing with ultrasonic diagnosis ot heart and circulatory failures. The rapid devel(~pn~ent of ultrasonic was well demonstrated in a tutorial Filipc/ynski (Poland) on medical
il~gli~)st~~ methods review paper by L. ultrasonic imaging.
Perhaps the most interesting paper among the post-deadline papers of this session was the report by S.T. Shac (China) on their experimental work on liquid surface acoustic holography with pulsed laser illumination. Seeing the film he presented the general opinion was that they had achieved the limit that can practically be achieved with this acoustic imaging technique. Another post-deadline paper- dealing with acoustic holopraphy of biological objects presented by G.A. KarauridLe
92
Type 3401 . Kran;/buhler ant! Sohn their real-[ime sc;lnneI ADR. the Italian BIMIO Tonol~ represented rhe 4dvanccl!
ULTRASONICS
MARCH
1980
Technology Laboratories, Inc., Bellevue, Wa., showing their whole range of ultrasonic diagnostic equipment, Kretztechnik demonstrated its sector scanner, and Medata AB distributed literature on the products it represents.
Although the exhibition was not held at the conference site, time was allotted for the participants to visit the exhbition. Visiting local medical doctors had the opportunity to test the various instruments on their own patients. P. Greguss
Underwater applications of non-linear acoustics University
of Bath, UK lOth-11th
September 1979
This conference was arranged by the Underwater Acoustics Group of the Institute of Acoustics and was well attended by 60 delegates drawn from many countries. The first paper, an invited one, by W.L. Konrad (NUSC, New London, USA) reviewed some of the more important uses of the parametric source and discussed most of them in terms of full scale applications. Detection and echo ranging systems that employ compact, battery powered parametric sources for use by divers were described. Tape recorded music and speech was played which convincingly demonstrated the data rate improvement possible using the wide bandwidth/narrow beamwidth capability of nonlinear sources compared with conventional ones. H.B. Braithwaite (Ulvertech, UK), with co-authors H.O. Berktay (University of Bath, UK) B.V. Smith (University of Birmingham, UK) and M. Whitehouse (University of Birmingham, UK) then described a sub-bottom profiling system using parametric sources. Difference frequency chirp pulses were used centred on 5, 10 or 15 kHz with a 6.6 kHz frequency sweep in 1.65 ms; a 300 kHz transducer was employed. Results obtained with the system mounted on a manned submersible were presented. In the last paper of the first session R.V. Ceen with coauthor N.G. Pace (both of Bath University, UK) described a simple time-domain model of the parametric array operating in the ‘self-demodulation’ mode. Observations of a waterborne parametric array using both a water-borne hydrophone and a hydrophone buried in water-saturated sand were presented and discussed in relation to the time-domain model. The second session began with B.V. Smith (University of Birmingham, UK) and co-authors H.O. Berktay, B.S. Cooper and J.R. Dunn who presented a sample of experimental results on the near-field behaviour of finite amplitude waves radiated from rectangular transducers of various aspect ratios, and discussed them in terms of existing theoretical models. WI. Roderick (NUSC, New London, USA) described the measurement of the acoustical signal losses and fluctuations via reflection from the ocean boundaries. The use of a parametric source (mean primary frequency 263 kHz) operating at a difference frequency of 10, 20 or 30 kHz allowed the detrimental effects of multipath interference to be virtually eliminated. J.M. Hovem (University of Trondheim, Norway) described the possible sources of non-linearity in marine sediments and showed how the acoustic parameter of non-linearity (B/A) can be expressed as a weighted sum of contributions from the pore fluid, the solid and the frame.
ULTRASONICS.
MARCH
1980
The following day, the third session began with a contribution by S. Tj$tta and J.N. Tj$tta (University of Bergen, Norway) to the theory of parametric acoustic arrays. Simplified equations were presented, obtained using pertubation methods, which govern the sound field generated by the non-linear interaction of two coaxial, bounded sound beams taking into account diffraction, non-linearity and dissipation when the source of the interacting waves is a circular piston. This was followed by another theoretical paper, by J.F. Scott (University of Leeds, UK) on the amplitude saturation of spherical non-linear waves. The last paper in this session was by R.H. Mellen and M.B. Moffett (NUSC New London, USA) in which a numerical model of the parametric radiator was presented. The model, which is capable of rapid evaluation, permits the inclusion of an amplitude taper function to account for saturation effects. Model predictions were compared with experimental results. The parametric receiving array (PARRAY) was admirably reviewed by T.G. Goldsberry (ARL, Texas, USA) in an invited paper. Emphasis was placed on the reasons and methods for the careful selection of not only the system parameters but also the stringent performance requirements of electronic sub-systems. Various points made in the presentation were underlined by experimental results obtained over a frequency range 35 to 800 Hz using a 340 m pumphydrophone separation. C.R. Culbertson (ARL, Texas, USA) followed with a clear account of the parametric receiving array in an inhomogeneous medium. Experimental results of received signal amplitude fluctuations obtained in a model study were in good agreement with theory. The final topic of the conference was lucidly presented by T.G. Muir (ARL, Texas) in an invited paper entitled ‘Some simple propagation models for linear and parametric sources in shallow water’. Tne important role of narrow beams in the shallow water environment was further emphasized in the final paper by L. Bj$rn$ and co-authors A. Hartig, H.H. Jensen and P.N. Larsen (Technical University of Denmark): a theoretical treatment of sound propagation in temperature stratified shallow water was described together with results from an experimental laboratory programme using parametric acoustic arrays. The proceedings of the conference are available from J. Mills, Publications Secretary, Underwater Acoustics Group, Bell Electronics, John Scott House, Market Street, Bracknell, Berkshire, UK: price Lg.00 including postage and packing. N.G. Pace
93
Angelini explained that he was referring to health surveillance. Stressing the apparent safety of diagnostic ultrasonic procedures, and their relatively low costs. hc explained that ultrasonic screening of individual patients presenting at llis clinic with particular clinical problems had revealed a significant number of unsuspected abn~~rlnalities. Thus. in the 2.500 diagnostic ultrasonic examinations carried out in his unit in 1978. unsuspected lesions had been discovet-ed in the liver, gaIl-bladder, bile ducts, pancreas, spleen, abdominal aorta. kidneys, bladder, prostate and uterus. The additional examination time required to ‘screen‘ these organs in each patient is only about 10 minutes. P. N. T. Wells
Fourth ultrasound in biology and medicine symposium Visegrad, Hungary, 25-28
September
1979
This fourth ultrasound in biology and medicine symposium under the auspices of the Hungarian Biophysical Society and the Applied Biophysics Laboratory of the Technical University Budapest had an attendance of nearly 90 from 13 different countries. The meeting embraced four sessions. each of which was introduced by an invited speaker, who gave a tutorial-critical review of the session’s main topic, including the papers published in Volume I of the Sytnposium Proceedings. Since this volume was distributed before the opening of the Symposium, each author of the reviewed paper had only 5 min to round off his paper by presenting new data. showing slides or figures not included in the Proceedings, etc, so there was more time for discussion than is usually the case in such meetings. In the intrL)du~t~)ry lecture P. Greguss (Hungary) comnlcmoi-ated the 30th anniversary of the Italian abbot L.a/./arc~ Spalanzani. who first demonstrated experimentally that bat5 may use sound waves for (~rieil~arion and target recognition. In this talk, the question was raised whether what had been learned since Spalanzani about echolocating animals could be used to improve uitrasonic diagnostics and intluence the design philosophy of these instruments. The was definitely positive. answer, although controversial.
and Sl1.D. Kakichashvili (LJSSR) described a new holographic technique which allows the visualization of the holographic irif~~rllla~~~~nwithout using an acoustic reference wave. The technique is based on the diffraction of light on the disturbed interface of two media. Although the description of the tecllnique was not discussed in detail, the re~~~nstrllcte(l images showed higher quality than the reconstru~tecl images WCal-e accustomed to see from conventional acoustical holographiz ~Il?aging techniques. Session II. the review papet- c)t‘wtiicll was read h?/ R. Millnci (GDR) was devoted to ultrasonic hi~mef 1-y :ttld tissue signature. MMOSI of the post-deadline papel-s were pt-esentc~l in this session. Discussions in this session wcrt’ merely 01 clinical nature rather tlian technical or physical.
Oiity two post-deadline
papers ark-ivccl to these t\st~ \iGtklt\.
The introductory paper on ultrasonic techniques for the investigation of carotid and vertebl-al artery diseases hy 13.N. White (Canada) was a good basis for those post-deadline papers that were dealing with ultrasonic diagnosis ot heart and circulatory failures. The rapid devel(~pn~ent of ultrasonic was well demonstrated in a tutorial Filipc/ynski (Poland) on medical
il~gli~)st~~ methods review paper by L. ultrasonic imaging.
Perhaps the most interesting paper among the post-deadline papers of this session was the report by S.T. Shac (China) on their experimental work on liquid surface acoustic holography with pulsed laser illumination. Seeing the film he presented the general opinion was that they had achieved the limit that can practically be achieved with this acoustic imaging technique. Another post-deadline paper- dealing with acoustic holopraphy of biological objects presented by G.A. KarauridLe
92
Type 3401 . Kran;/buhler ant! Sohn their real-[ime sc;lnneI ADR. the Italian BIMIO Tonol~ represented rhe 4dvanccl!
ULTRASONICS
MARCH
1980
Technology Laboratories, Inc., Bellevue, Wa., showing their whole range of ultrasonic diagnostic equipment, Kretztechnik demonstrated its sector scanner, and Medata AB distributed literature on the products it represents.
Although the exhibition was not held at the conference site, time was allotted for the participants to visit the exhbition. Visiting local medical doctors had the opportunity to test the various instruments on their own patients. P. Greguss
Underwater applications of non-linear acoustics University
of Bath, UK lOth-11th
September 1979
This conference was arranged by the Underwater Acoustics Group of the Institute of Acoustics and was well attended by 60 delegates drawn from many countries. The first paper, an invited one, by W.L. Konrad (NUSC, New London, USA) reviewed some of the more important uses of the parametric source and discussed most of them in terms of full scale applications. Detection and echo ranging systems that employ compact, battery powered parametric sources for use by divers were described. Tape recorded music and speech was played which convincingly demonstrated the data rate improvement possible using the wide bandwidth/narrow beamwidth capability of nonlinear sources compared with conventional ones. H.B. Braithwaite (Ulvertech, UK), with co-authors H.O. Berktay (University of Bath, UK) B.V. Smith (University of Birmingham, UK) and M. Whitehouse (University of Birmingham, UK) then described a sub-bottom profiling system using parametric sources. Difference frequency chirp pulses were used centred on 5, 10 or 15 kHz with a 6.6 kHz frequency sweep in 1.65 ms; a 300 kHz transducer was employed. Results obtained with the system mounted on a manned submersible were presented. In the last paper of the first session R.V. Ceen with coauthor N.G. Pace (both of Bath University, UK) described a simple time-domain model of the parametric array operating in the ‘self-demodulation’ mode. Observations of a waterborne parametric array using both a water-borne hydrophone and a hydrophone buried in water-saturated sand were presented and discussed in relation to the time-domain model. The second session began with B.V. Smith (University of Birmingham, UK) and co-authors H.O. Berktay, B.S. Cooper and J.R. Dunn who presented a sample of experimental results on the near-field behaviour of finite amplitude waves radiated from rectangular transducers of various aspect ratios, and discussed them in terms of existing theoretical models. WI. Roderick (NUSC, New London, USA) described the measurement of the acoustical signal losses and fluctuations via reflection from the ocean boundaries. The use of a parametric source (mean primary frequency 263 kHz) operating at a difference frequency of 10, 20 or 30 kHz allowed the detrimental effects of multipath interference to be virtually eliminated. J.M. Hovem (University of Trondheim, Norway) described the possible sources of non-linearity in marine sediments and showed how the acoustic parameter of non-linearity (B/A) can be expressed as a weighted sum of contributions from the pore fluid, the solid and the frame.
ULTRASONICS.
MARCH
1980
The following day, the third session began with a contribution by S. Tj$tta and J.N. Tj$tta (University of Bergen, Norway) to the theory of parametric acoustic arrays. Simplified equations were presented, obtained using pertubation methods, which govern the sound field generated by the non-linear interaction of two coaxial, bounded sound beams taking into account diffraction, non-linearity and dissipation when the source of the interacting waves is a circular piston. This was followed by another theoretical paper, by J.F. Scott (University of Leeds, UK) on the amplitude saturation of spherical non-linear waves. The last paper in this session was by R.H. Mellen and M.B. Moffett (NUSC New London, USA) in which a numerical model of the parametric radiator was presented. The model, which is capable of rapid evaluation, permits the inclusion of an amplitude taper function to account for saturation effects. Model predictions were compared with experimental results. The parametric receiving array (PARRAY) was admirably reviewed by T.G. Goldsberry (ARL, Texas, USA) in an invited paper. Emphasis was placed on the reasons and methods for the careful selection of not only the system parameters but also the stringent performance requirements of electronic sub-systems. Various points made in the presentation were underlined by experimental results obtained over a frequency range 35 to 800 Hz using a 340 m pumphydrophone separation. C.R. Culbertson (ARL, Texas, USA) followed with a clear account of the parametric receiving array in an inhomogeneous medium. Experimental results of received signal amplitude fluctuations obtained in a model study were in good agreement with theory. The final topic of the conference was lucidly presented by T.G. Muir (ARL, Texas) in an invited paper entitled ‘Some simple propagation models for linear and parametric sources in shallow water’. Tne important role of narrow beams in the shallow water environment was further emphasized in the final paper by L. Bj$rn$ and co-authors A. Hartig, H.H. Jensen and P.N. Larsen (Technical University of Denmark): a theoretical treatment of sound propagation in temperature stratified shallow water was described together with results from an experimental laboratory programme using parametric acoustic arrays. The proceedings of the conference are available from J. Mills, Publications Secretary, Underwater Acoustics Group, Bell Electronics, John Scott House, Market Street, Bracknell, Berkshire, UK: price Lg.00 including postage and packing. N.G. Pace
93