Illustrated Computer Tomography : A Practical Guide to CT Interpretations

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.

I. Basic Aspects of Computed Tomography.- 1 Debut and Spread.- 1.1 History ― Rotation Radiography and Computed Tomography.- 1.2 Utility of CT.- 1.3 Current Status and Future Scope of CT Applications.- 2 Principles.- 2.1 Principles of CT Imaging.- 2.2 Theory of Image Reconstruction.- 2.2.1 Matrix Inversion.- 2.2.2 Iterative Approximation.- 2.2.3 Back Projection.- 2.2.4 Filtered Back Projection.- 2.2.5 Various Problems Regarding Image Reconstruction.- 2.3 CT Images and Their Evaluation.- 3 CT Scanner.- 3.1 Basic Function.- 3.2 Main Subsystems.- 3.2.1 X-ray Tube and X-ray Generator.- 3.2.2 Detector and Collection of Data.- 3.2.3 Computer.- 3.2.4 Magnetic Disk Unit.- 3.2.5 Magnetic Tape Unit.- 3.2.6 Display.- 3.2.7 Independent Viewing Console.- 3.2.8 Hard Copy.- 3.2.9 Printer.- 3.2.10 The Patient’s Couch and Patient Positioning.- 4 Performance Evaluation.- 4.1 Items for Performance Evaluation.- 4.1.1 Noise.- 4.1.2 Contrast Scale.- 4.1.3 Spatial Resolution.- 4.1.4 Artifact.- 4.1.5 Uniformity.- 4.1.6 Linearity.- 4.1.7 Size Independence.- 4.1.8 Reproducibility and Quality Assurance.- 4.2 Examples of Actual Performance Evaluations.- 4.2.1 Noise and Contrast Scale.- 4.2.2 Spatial Resolution.- 4.2.3 Uniformity and Size Independence.- 4.2.4 Reproducibility and Quality Assurance.- 5 Actual Procedure of the Performance of CT and Its Interpretation.- 5.1 Patient Selection and Reservation for CT Examinations.- 5.2 Preparation.- 5.3 Fixation of the Patient in Position.- 5.4 Positioning by Means of a Standard Line.- 5.5 Determination and Confirmation of the Scanning Level.- 5.6 Contrast Media and Their Effect.- 5.7 CT Image Observation.- 5.8 Window Width and Window Level.- 5.9 Measurement of CT Numbers.- 5.10 Artifact.- 5.11 Effects of the Calculation Method on Image Formation.- 5.12 Special Observation Techniques.- 6 Exposure Dosage.- 6.1 Risk Assessment of CT Examinations.- 6.2 Factors Determining CT Exposure.- 6.2.1 Unit Characteristics.- 6.2.2 Selection of Scanning Method.- 6.2.3 Physician’s Specifications on CT Procedures.- 6.3 Dosimetric Methods for Estimating CT Exposure.- 6.4 Dose Distribution.- 6.5 Distribution of Scattered and Leakage Radiations in the CT Room.- 6.6 Reduction of Patient Doses in CT.- II. Atlas of Computed Tomography of the Normal Adult.- 1 Orientation and Interpretation of CT Images.- 1.1 Head.- 1.2 Face.- 1.3 Neck.- 1.4 Chest.- 1.5 Abdomen.- 2 Axial Transverse Cross Section Figures of the Normal Adult.- III. Clinical Application of Computed Tomography.- 1 CT Images of Lesions.- 1.1 Difference in Density.- 1.1.1 High Density.- 1.1.2 Isodensity.- 1.1.3 Low Density.- 1.2 Morphology of Image.- 1.2.1 Circular Images.- 1.2.2 Lens and Semilunar-Shaped Images.- 1.2.3 Irregularly Shaped Images.- 1.2.4 Digital-Shaped Images.- 2 Computed Tomography of Diseases.- 2.1 Diseases of the Brain.- 2.1.1 Cerebral Tumor.- 2.1.2 Cerebrovascular Diseases.- 2.1.3 Trauma of the Head.- 2.1.4 Intracranial Infections (Infectious Diseases of the Brain).- 2.1.5 Other Intracerebral Diseases.- 2.2 Diseases of the Optic Fossa.- 2.3 Diseases of the Head and Neck.- 2.3.1 Temporal Bone and Skull Base.- 2.3.2 Paranasal Sinuses, Nasal Cavity, and Face.- 2.3.3 Pharynx and Larynx.- 2.3.4 Neck, Thyroid, and Parathyroid Glands.- 2.4 Diseases of the Thorax.- 2.4.1 Aorta and Pericardium.- 2.4.2 Mediastinum.- 2.4.3 Lung.- 2.4.4 Thoracic Wall and Pleura.- 2.5 Diseases of the Abdomen Including the Pelvis.- 2.5.1 Liver.- 2.5.2 Gallbladder and Bile Duct.- 2.5.3 Spleen.- 2.5.4 Pancreas.- 2.5.5 Kidney.- 2.5.6 Adrenal Glands.- 2.5.7 Peritoneal Cavity and Intestines.- 2.5.8 Retroperitoneum.- 2.5.9 Pelvic Organs.- 2.6 Diseases of the Spine, Spinal Cord, and Extremities.- 2.6.1 Spine.- 2.6.2 Spinal Cord.- 2.6.3 Extremities.- IV. Radiotherapy Planning and Computed Tomography.- 1 Determination of the Site and Extent of the Lesion and the Surrounding Healthy Tissues.- 2 Difference Between CT Images for Radiation Therapy and Those for Diagnostic Purposes.- 3 Technical Requirements for Radiotherapy-Orientated CT Scanning.- 3.1 Improvement of the CT Scanner Couch.- 3.2 Side Localizers and Front Localizer.- 3.3 Fixation of the Patient.- 3.4 Skin Markers.- 3.5 Superimposition of Two CT Images.- 4 Planning of Treatment Using CT.- 5 CT-linked Treatment Planning System.- 6 Inhomogeneity Corrections Using CT Images in Dose Distributions.- References.