The publication of proceedings of conferences has often been so delayed that they are useless both to active workers in the field and for cur­ rently appropriate teaching. Rapid publication on the other hand may impose very difficult conditions upon authors and demand unwelcome sacrifices. We wish to thank the many speakers at ESCAT for their co­ operation in providing manuscripts and to apologise to those unable for reasons beyond their control to fall in with the rigorous editorial policy. To get this book out at the earliest possible moment we have also cut the normal consultation between editors and authors to a minimum. One decision made in the interests of uniformity was to re­ place the various terms used by different writers by one, C. A. T. , consistent with the title of the Seminar of which the book is arecord. The organisers of ESCAT decided upon a largely didactic meeting with as little overlap as was practicable between contributions and a de­ termined attempt to view computerised axial tomography in the light of its clinical usefulness. As consequence, the purpose of this book is to provide a comprehensive introduction to the whole field for clin­ icians as weIl as radiologists. The editors wish to acknowledge the very efficient help and encourage­ ment of the publishers and the hard secretarial work of Miss G. JOHNS, as weIl as the editorial assistance of Dr. DEREK KINGSLEY. London, Spring 1977 G. H. DU BOULAY . I. F.