A data processing method of determining a treatment plan, the treatment plan describing a medical treatment to be carried out on a patient, the steps of the method being executed by a computer and comprising: a. acquiring current patient data comprising current patient information about a current patient's body; b. acquiring, based on the current patient data, reference patient data comprising image information about a geometry of a body of a reference patient; c. determining, based on the current patient data and the reference patient data, applicability data comprising applicability information about an applicability of the image information contained in the reference patient data to the image information contained in the current patient data; d. acquiring, based on the reference patient data and the applicability data, reference treatment plan data comprising reference treatment plan information about a reference treatment plan; e. determining, based on the current patient data and reference treatment plan data, current treatment plan data comprising current treatment plan information about a medical treatment to be carried out on the current patient, wherein determining the current treatment plan data comprises adapting the reference treatment plan data based on the current patient data, characterized by acquiring approval template data comprising approval template information that describes an approval template containing acceptance and advantageously rejection criteria for the current treatment plan information; determining criteria fulfillment data comprising criteria fulfillment information describing whether the current treatment plan information fulfils the criteria described by the approval template information or not; and accepting the current treatment plan information for carrying out the medical treatment on the patient if the criteria fulfillment information indicates that the current treatment plan information fulfils the criteria described by the approval template information, otherwise rejecting the current treatment plan information for further use in the medical treatment. a. acquiring current patient data comprising current patient information about a current patient's body; b. acquiring, based on the current patient data, reference patient data comprising image information about a geometry of a body of a reference patient; c. determining, based on the current patient data and the reference patient data, applicability data comprising applicability information about an applicability of the image information contained in the reference patient data to the image information contained in the current patient data; d. acquiring, based on the reference patient data and the applicability data, reference treatment plan data comprising reference treatment plan information about a reference treatment plan; e. determining, based on the current patient data and reference treatment plan data, current treatment plan data comprising current treatment plan information about a medical treatment to be carried out on the current patient, wherein determining the current treatment plan data comprises adapting the reference treatment plan data based on the current patient data,