1. A method for the reconstruction of a dose administered to an object to be irradiated, the method comprising: recording a computed tomography image of the object to be irradiated with a single or multi slice computed tomography scanner, the single or multi slice computed tomography scanner comprising a kV x-ray source and an opposite kV detector for producing a computed tomography of the object positioned in a radiation therapy device, the radiation therapy device comprising a therapeutic radiation source for emitting a therapeutic treatment beam, and a portal detector opposing the therapeutic radiation source for recording measurement data of the treatment beam once the treatment beam has left the object to be irradiated; and reconstructing the dose administered to the object from measurement data of the portal detector using the computed tomography image.