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Acoustical imaging
the EEG is unjustified since almost invariably little is known of the complex phase response of the tortuous electronic pathway through which the signal passes. The large variance of high definition spectral estimates permits only a low confidence. Most of those who work in the EEG world have grown accustomed to differences amongst clinicians over the interpretation of clinical records; it came as something of a surprise to find argument and similar differences of opinion among statisticians discussing the validity and interpretation of their results. Discussion was brisk and uninhibited, one of the advantages of a small group, but above all considerable credit must go to the omnipresent but rarely seen simultaneous interpreters. To translate medicine, physiology and psychology is no doubt difficult, as is the translation of mathematics and
engineering, but to combine all in a simultaneous three language translation, when on occasions the speaker is not using his native language, merits the highest appreciation; without that competent service the conference would not have been the success it certainly was. Dr. Court deserves the thanks of all for the conference organisation. Much more was discussed than is reported here, enquiries concerning the abstracts should be addressed to Monsieur le Medecin en Chef L Court, Division de Radiobiologie e Radioprotection, Centre de Recherches du Service de Sante Armees, 1 bis rue due Lieutenant Raoul Batany, 92 14 1 Clamart, France. The complete papers will be published in book form in English. GH. Bvford
ACOUSTICAL IMAGING Eds M. Kaveh, E.K. Mueller
and J.F. Greenleaf
Plenum Publishing Co?-, New York, 1984, $89.50 This volume of papers is the proceedings of the 13 th International Symposium on Acoustical Imaging held in Minneapolis in October 1983. Some 48 papers are included covering such topics as the theory of acoustic propagation and scattering, the theory of image reconstruction, tissue and material characterization, acoustic microscopy, transducers, imaging systems and signal processing. Apart from six papers which, regrettably, are in abstract form only, the length of the contributions are quite reasonable, typically 15 pages. The quality of the copy is variable since this volume was assembled from submitted manuscripts using photocopy techniques but on the whole is good. These proceedings along with the proceedings from the twelve preceding symposia clearly form an important source of information for anyone working in this area This volume identifies the principal problem areas currently of interest. However, there are no review papers and none of the contributions can be considered to be introductory in nature so this volume would not be easy reading for a novice in this field. The general scientific standard of the contributions to these proceedings appears high. The content of such a volume is determined partly by the selection committee but largely by the nature of the papers submitted to the symposium. Such a volume should therefore reflect reasonably accurately the current state of the subject. What is interesting about this volume is that for a book on imaging it contains relatively few images and most of those that are included are either from simulated data or from data taken from laboratory
phantoms. In fact the whole volume is heavy with theory and light on practice. The reason for this situation is not really tackled by any of the authors but is I suspect due to the coupling problem. The problem of coupling the transducer to the medium being investigated is a fundamental problem with acoustical imaging, especially in the medical field and especially if large area transducers (or scanning transducers) are being used as in the case of coherent imaging techniques or tomographic techniques. Using a water bath is rarely satisfactory, especially for routine medical applications. The most successful acoustical imaging technique to date, that of pulsed echo imaging has achieved its success largely because the coupling roblem has been solved for this method. The de Pects of this technique are well known, especially the fact that it does not achieve the resolution theoretically possible for the wavelengths being used and it is not possible to quantitatively extract information such as attenuation from the detected signals, but poor images are better than none. The only paper in this volume which arrives close to appreciating this point is that of Leeman and Jones. It is clear that more attention needs to be given to imaging techniques which only require a limited amount of coupling if acoustical imaging is to realise its full potential. Nevertheless, having made this point, this volume shows that the field of acoustical imaging is clearly a very active one and this book is essential reading for workers in this area They can reasonably look forward to the proceedings of the 14th Symposium with pleasurable anticipation. D. C. Barber Royal Hallamshire Hospital Shzfield
J. Biomed.
Eng. 1985, Vol. 7, July
261
engineering, but to combine all in a simultaneous three language translation, when on occasions the speaker is not using his native language, merits the highest appreciation; without that competent service the conference would not have been the success it certainly was. Dr. Court deserves the thanks of all for the conference organisation. Much more was discussed than is reported here, enquiries concerning the abstracts should be addressed to Monsieur le Medecin en Chef L Court, Division de Radiobiologie e Radioprotection, Centre de Recherches du Service de Sante Armees, 1 bis rue due Lieutenant Raoul Batany, 92 14 1 Clamart, France. The complete papers will be published in book form in English. GH. Bvford
ACOUSTICAL IMAGING Eds M. Kaveh, E.K. Mueller
and J.F. Greenleaf
Plenum Publishing Co?-, New York, 1984, $89.50 This volume of papers is the proceedings of the 13 th International Symposium on Acoustical Imaging held in Minneapolis in October 1983. Some 48 papers are included covering such topics as the theory of acoustic propagation and scattering, the theory of image reconstruction, tissue and material characterization, acoustic microscopy, transducers, imaging systems and signal processing. Apart from six papers which, regrettably, are in abstract form only, the length of the contributions are quite reasonable, typically 15 pages. The quality of the copy is variable since this volume was assembled from submitted manuscripts using photocopy techniques but on the whole is good. These proceedings along with the proceedings from the twelve preceding symposia clearly form an important source of information for anyone working in this area This volume identifies the principal problem areas currently of interest. However, there are no review papers and none of the contributions can be considered to be introductory in nature so this volume would not be easy reading for a novice in this field. The general scientific standard of the contributions to these proceedings appears high. The content of such a volume is determined partly by the selection committee but largely by the nature of the papers submitted to the symposium. Such a volume should therefore reflect reasonably accurately the current state of the subject. What is interesting about this volume is that for a book on imaging it contains relatively few images and most of those that are included are either from simulated data or from data taken from laboratory
phantoms. In fact the whole volume is heavy with theory and light on practice. The reason for this situation is not really tackled by any of the authors but is I suspect due to the coupling problem. The problem of coupling the transducer to the medium being investigated is a fundamental problem with acoustical imaging, especially in the medical field and especially if large area transducers (or scanning transducers) are being used as in the case of coherent imaging techniques or tomographic techniques. Using a water bath is rarely satisfactory, especially for routine medical applications. The most successful acoustical imaging technique to date, that of pulsed echo imaging has achieved its success largely because the coupling roblem has been solved for this method. The de Pects of this technique are well known, especially the fact that it does not achieve the resolution theoretically possible for the wavelengths being used and it is not possible to quantitatively extract information such as attenuation from the detected signals, but poor images are better than none. The only paper in this volume which arrives close to appreciating this point is that of Leeman and Jones. It is clear that more attention needs to be given to imaging techniques which only require a limited amount of coupling if acoustical imaging is to realise its full potential. Nevertheless, having made this point, this volume shows that the field of acoustical imaging is clearly a very active one and this book is essential reading for workers in this area They can reasonably look forward to the proceedings of the 14th Symposium with pleasurable anticipation. D. C. Barber Royal Hallamshire Hospital Shzfield
J. Biomed.
Eng. 1985, Vol. 7, July
261