Method for drawing up an irradiation plan for a particle therapy installation comprising a particle beam comprising protons, carbon ions or other ions, comprising the following steps: a) providing an image data record of the target object to be irradiated, comprising a target volume, by the particle beam comprising the protons, the carbon ions or the other ions, b) predetermining a target volume imaged in the image data record and a condition to be satisfied, c) performing an optimization method for establishing a parameter set by means of which the particle therapy installation is controllable, with the parameter set being optimized during the optimization method in respect of the condition to be satisfied using the image data record and calculation steps being performed to this end, which calculation steps characterize the effect of the particle beam on the target object, characterized by: d) producing an irradiation planning data record by virtue of the optimized parameter set being stored in the irradiation planning data record, with, in addition to the optimized parameter set, at least some of the intermediate results, which were established when performing the calculation steps when establishing the optimized parameter set, being stored in the irradiation planning data record together with the parameter set, with the intermediate results being partial results from which the obtainable dose distribution or a variable derived therefrom can be established in further calculation steps and these intermediate results not being for direct use in the control of the particle therapy installation, and these intermediate results being included in a new calculation if the irradiation plan is to be recalculated. a) providing an image data record of the target object to be irradiated, comprising a target volume, by the particle beam comprising the protons, the carbon ions or the other ions, b) predetermining a target volume imaged in the image data record and a condition to be satisfied, c) performing an optimization method for establishing a parameter set by means of which the particle therapy installation is controllable, with the parameter set being optimized during the optimization method in respect of the condition to be satisfied using the image data record and calculation steps being performed to this end, which calculation steps characterize the effect of the particle beam on the target object, characterized by: d) producing an irradiation planning data record by virtue of the optimized parameter set being stored in the irradiation planning data record, with, in addition to the optimized parameter set, at least some of the intermediate results, which were established when performing the calculation steps when establishing the optimized parameter set, being stored in the irradiation planning data record together with the parameter set, with the intermediate results being partial results from which the obtainable dose distribution or a variable derived therefrom can be established in further calculation steps and these intermediate results not being for direct use in the control of the particle therapy installation, and these intermediate results being included in a new calculation if the irradiation plan is to be recalculated.