A method of generating and/or providing data (28) for tissue treatment, in particular a tumor treatment, via a low-energy irradiation appliance (10) is described. Herein, the low-energy irradiation appliance (10) has a radiation source (14) for generating soft radiation, preferably of a radiation with a spectrum from 0 to a maximal radiation energy of 100 keV, in particular a radiation with a spectrum from 0 to a maximal radiation energy of 50 keV and an emitting device (15) for emitting the radiation to tissue, which is to be irradiated. The method is characterized by the following steps: physical data of the radiation source (14) is determined directly from leaving the emitting device (15) quality data of the tissue, for example the tumor tissue and/or the tissue (17) in the vicinity of the tumor, is determined physical property data of the determined tissue is determined in connection with the radiation of the radiation source (14). Data (28) for the tissue treatment, for example the tumor treatment, is generated from the determined data and/or the determined data is provided for generating data for the tissue treatment, in particular tumor treatment.
