X-Ray and X-Ray-CT

Since their discovery in 1895, X-rays have been widely used for imaging humans. Recently, they have also gained an importance in small animal imaging (SAI). Most techniques known from clinical medicine, including single- and dual-energy X-ray imaging, have been successfully ported to SAI and are the subject of this chapter. As trivial as it is, simple X-ray examinations may bring diagnostically valuable information in a variety of applications. Unenhanced radiography reveals skeletal anatomy, contrast-enhanced imaging allows improved visualization of the vasculature and strongly vascularized areas, and dedicated methods such as bone densitometry deliver quantitative information. In analogy to clinical X-ray imaging, we will separately describe standard two-dimensional (2D) projection imaging and the more advanced three-dimensional (3D) computed tomography (CT) imaging techniques. Also in analogy to clinical applications, CT is considered to be of significantly higher importance as it provides more information and possibilities than conventional 2D approaches. It will therefore be covered in much more detail.