Nonlinearity and Inhomogenity Effects in Computerized Tomography Due to the Exponential Attenuation of Radiation

The known image reconstruction procedures in X-ray CT require a linear behaviour of the measuring system. Naturally this condition can only be fulfilled approximately. Deviations from the linear behaviour are causing image artifacts, which, according to experience, show a striking similarity in appearance in spite of quite different physical causes. A unified mathematical description of the non linear phenomena is therefore not only desirable but seems to be also possible.