The invention provides for a therapeutic apparatus comprising a tissue heating system (302, 480, 482). The therapeutic apparatus further comprises a magnetic resonance imaging system (300) for acquiring magnetic resonance thermometry data (366) from nuclei of a subject (318) located within an imaging volume (330). The therapeutic apparatus further comprises a radiation therapy system (304, 592) for irradiating an irradiation volume (316, 516) of the subject, wherein the irradiation volume is within the imaging volume. The therapeutic apparatus further comprises a controller (354) for controlling the therapeutic apparatus. The controller is adapted for acquiring (100, 210) magnetic resonance thermometry data repeatedly using the magnetic resonance imaging system. The controller is adapted for heating (102, 208) at least the irradiation volume using the tissue heating system. The heating is controlled using the magnetic resonance thermometry data. The controller is adapted for irradiating (104, 208) the irradiation volume.
