A method for making a beam modifier to be used in radiation therapy includes defining a region of interest in a patient that is to receive radiation, with the region of interest being defined using an anatomy coordinate system format. Radiation treatment parameters are defined for the defined region of interest, and correspond to an initial type beam modifier to be coupled to an output of a radiation device. Design data on a beam modifier to be placed on the skin of the patient is generated, with the design data being based on the defined region of interest and the defined radiation treatment parameters for the defined region of interest. The design data is in the same anatomy coordinate system format as the defined region of interest that is to receive the radiation. The design data is treated as a new region of interest, and the radiation dosage to be applied to the new region of interest is re-calculated while taking into account the beam modifier to be placed on the skin of the patient.
