A method is provided for determining the stopping power from computed tomography scans. The method includes preparing computed tomography scans of a body region with two different recording energies; determining the stopping power for different CT numbers from dual energy image areas of the computed tomography scans; forming a data field in which the determined values for the stopping power for different CT numbers from dual energy image areas are applied as a function of the CT numbers; forming a look-up table from the data field; determining the stopping power for different CT numbers from single energy image areas of the computed tomography scans by the look-up table. A corresponding device and control device, a corresponding particle therapy system, and a corresponding computed tomography system, are also provided.