A medical apparatus (1), particularly suitable for the treatment of a breast cancer, which apparatus (1) comprises: - a support (2) for a patient, such as to expose a breast in a predetermined position (20) of the support； - an imaging unit (3), configured in such a way as to provide, in use, a 3D image of the breast； - a treatment unit (4), comprising delivery means (41) of a ionizing radiation beam and configured so as to provide, in use, said beam at the breast； - a control unit (100) of said imaging unit (3) and/or treatment unit (4), configured to determine the delivery of a radiation beam with a shape dependent upon the image of the target body district supplied by said imaging unit (3).
