ABSTRACT
This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book discusses digital radiography and generally refers to the acquisition of conventional X-ray projection images in numerical form, readily permitting digital display, format manipulations, and mathematical analyses of the image data by computer. It describes X-ray-computed tomography. It is the most mature and best known of the new three-dimensional imaging modalities. The book discusses the basic method, which involves determination of the two-dimensional or three-dimensional distribution of X-ray densities within the body by mathematically processing in computer X-ray transmission measurements from many angles through the body provided by an X-ray scanning instrument. It describes the detection can be made either of single emitted photons or of positrons emitted in coincidence. The book shows that ultrasound techniques have been developed to provide three-dimensional medical images using computed tomography.
