ABSTRACT
This chapter describes the principles behind the various imaging modalities currently in use and the various measurements routinely made with them. The vast majority of imaging procedures are qualitative in nature, where it is the visual presentation of anatomy that is the measurement outcome. There are three primary physical parameters of interest in image content: contrast, noise, and resolution. A linear-systems approach is typically used to quantify the performance of an imaging system. X-ray imaging requires an x-ray-generating apparatus (tube, high-voltage supply, and controls) and an appropriate x-ray detector. The most common detector for x-ray imaging was film. X-ray film was typically placed in a sandwich between two fluorescent screens (or one screen in mammography for improved visibility of small detail). A diagnostic computed tomography scanner comprises an x-ray tube with collimation to provide the slice thickness, a linear array of detector elements, and a reconstruction computer.
