A medical apparatus (300 400 500) comprises a high intensity focused ultrasound system(322) configured for for sonicating a target volume (340) of a subject (318). The medical apparatus further comprises a magnetic resonance imaging system (302) for acquiring magnetic resonance data (356 358 360 368 374) from an imaging zone (308). The treatment volume is within the imaging zone. The medical apparatus further comprises a memory(352) containing machine executable a control module (382 402) for controlling the sonication of the target volume using the magnetic resonance data as a control parameter and a processor (346). Execution of the instructions causes the processor to repeatedly acquire (102 202) magnetic resonance data in real time using the magnetic resonance imaging system and control(104 206) sonication of the target volume by the high intensity focused ultrasound system in real time using the sonication control module and the magnetic resonance data.
