The invention relates to a method for real-time-related correction of the spatial position of the central beam of radiotherapy devices and therapy simulators and of the patient position. In particular, the method relates to real time-related correction of irradiation positions of the collimator and/or the position of the patient couch during the radiotherapy or the therapy simulation. The problem addressed by the invention consists in the development of a method with which the position deviations of the central beam of available radiotherapy devices are reduced and the technical outlay required for the accuracy and the patient comfort is optimized in the process. This problem is solved by virtue of the control of the positions of the collimator elements and/or of the patient couch for optional further degrees of freedom of the movements being implemented by functional add-ons of separate control assemblies, the changes in the positions of the collimator elements and/or the patient couch being undertaken within the optional further degrees of freedom by means of separate adjustment devices that are added to the collimator and/or patient couch and connected to the control assemblies, and the calculation of the correction movements being carried out outside of the radiotherapy device in the irradiation planning system and/or in at least one microcontroller of the controller of the radiotherapy device.
