In spring this year it will be 35 years since I began to study rotation technique as applied to radiology. In 1947 the name rotation radiography was publicly adopted for the application of this technique to roentgenography. Since then our study has revealed that the technique in presenting the axial transverse cross section figure is valuable not only in diagnosis but also in radiotherapy. Our books on "Conformation Radiotherapy - Rotation Technique as Applied to Radiography and Radiotherapy of Cancer" and" An Atlas of Axial Trans verse Tomography and its Clinical Application" were published by Acta Radio logica, Stockholm in 1965 and Springer Verlag in 1969 respectively. Having excellent contrast resolution computed tomography can be considered an advan ced type of rotation radiography. With this in mind I planned to edit and publish the Illustrated Computer Tomography as the latest presentation in a series of publications on rotation radiography. The editor would like to express his deep appreciation to the contributors to this book as well as to the publishers Shujunsha, Japan and Springer Verlag. Spring 1983 SHINJI TAKAHASHI Contents Introduction. By S. TAKAHASHI . . . . . . . 1 Part I. Basic Aspects of Computed Tomography Debut and Spread. By S. TAKAHASHI.