A method for calculating loads deposited by an ionizing radiation, for example to be used by a radiotherapy therapeutic treatment device. The method includes at least one first step of calculating a function of the distribution of the load in the meshes of a mesh phantom. The method includes a second step of calculating the load deposited in a voxel assembly, the value of the deposited load for one voxel being given by the function of the distribution of the load particular to the mesh to which the voxel belongs. The invention can be used in particular for radiotherapy by intensity modulation.
