The invention relates to a method for the production of standardized tumor phantoms, and a method and a device for validating devices for medical-tomographic imaging systems. The invention serves to improve diagnosis, for monitoring the progress and the more specific determination of the exposure regions for a subsequent radiotherapy. The aim of the invention is to develop a mobile universally usable apparatus which can be used for a repeatable and reproducible 4D movement (in space and time) of a fully realistic phantom insert for measurements in medical-tomographic imaging systems, such as CT, PET, SPECT or MRT systems, and on radio-oncological accelerators. The apparatus for validating devices for medical-tomographic imaging systems consists of a body phantom for the simulation of a human body and a motion device for a tumor phantom in the interior of the body phantom. The motion device consists of a cinematic chain with at least two revolute joints and a sliding joint, which move the tumor phantom in three dimensions inside the body phantom on trajectories analogously to human respiration. The motion device consists of materials which have similar attenuation properties for gamma radiation as the surrounding fluid.