Tomography is an imaging method that allows to create images of the interior of an opaque object from measurements of the attenuation of x-rays after passing through the object. Mathematically this leads to the task of recovering a function from its integrals over lines. This talk will provide an introduction to pi-line reconstruction formulas in tomography and explore two of their characteristic features. The first is the so-called region of backprojection and the second a small but characteristic artifact in the images.