A method for planning to treat tissue by administering a substance which emits energy or can interact with administered energy to a body, such as body tissue, wherein a dispersion of the substance in the body is simulated, and to a system or device for planning administering a substance and administering energy to a body or in body tissue. The device includes a data capture unit configured to detect patient-specific parameters, wherein the patient-specific parameters can be used to describe a dispersion behavior of the substance in the body or body tissue a computational unit operatively coupled to the data capture unit, said computational unit configured to obtain the patient-specific parameters from the data capture unit a database accessible by the computational unit, wherein the database includes data for describing characteristics of a particular type of tissue or a particular body structure, data for describing mechanisms for supplying energy, and/or data for describing the effect on tissue of a substance in combination with supplied energy, the computational unit being configured to retrieve and/or store said data in the database and an input unit via which a user can input treatment-specific data to the computational unit, wherein the computational unit is configured to simulate the plan based on at least one of the patient-specific data, data stored in the database, or user input data.
