A medical instrument comprising: - a magnetic resonance imaging system operable for acquiring thermal magnetic resonance data from a subject at least partially located within an imaging zone of the magnetic resonance imaging system; - a high intensity focused ultrasound system wherein the high intensity focused ultrasound system has an adjustable focus, wherein the high intensity focused ultrasound system is operable for controlling the adjustable focus to sonicate the subject at multiple sonication points within the imaging zone; - a processor for controlling the high intensity focused ultrasound system and the magnetic resonance imaging system; - memory for storing machine executable instructions (270, 272, 274, 276, 278, 280) for execution by the processor, wherein execution of the instructions causes the processor to: - control the high intensity focused ultrasound system to sequentially sonicate the multiple sonication points to exceed a therapeutic threshold; - control the magnetic resonance imaging system to repeatedly acquire the thermal magnetic resonance imaging data; - repeatedly reconstruct multiple thermal maps using the thermal magnetic resonance imaging data; - determine a time dependent accumulated thermal dose distribution using the multiple thermal maps; - calculate a heating center of mass for each of the multiple thermal maps creating a set of heating center of masses, wherein the set of heating center of masses are calculated by searching for at least one maximum in the thermal dose distribution; - selecting several sonication points from the multiple sonication points for each member of the set of heating center of masses, wherein the one or more sonication points are selected using a predetermined criterion; - determine a spatially dependent targeting correction by comparing each member of the set of the heating center of masses to the one or more sonication points; and - control the high intensity focused ultrasound system to offset the adjustable focus by the spatially dependent targeting correction. - a magnetic resonance imaging system operable for acquiring thermal magnetic resonance data from a subject at least partially located within an imaging zone of the magnetic resonance imaging system; - a high intensity focused ultrasound system wherein the high intensity focused ultrasound system has an adjustable focus, wherein the high intensity focused ultrasound system is operable for controlling the adjustable focus to sonicate the subject at multiple sonication points within the imaging zone; - a processor for controlling the high intensity focused ultrasound system and the magnetic resonance imaging system; - memory for storing machine executable instructions (270, 272, 274, 276, 278, 280) for execution by the processor, wherein execution of the instructions causes the processor to: - control the high intensity focused ultrasound system to sequentially sonicate the multiple sonication points to exceed a therapeutic threshold; - control the magnetic resonance imaging system to repeatedly acquire the thermal magnetic resonance imaging data; - repeatedly reconstruct multiple thermal maps using the thermal magnetic resonance imaging data; - determine a time dependent accumulated thermal dose distribution using the multiple thermal maps; - calculate a heating center of mass for each of the multiple thermal maps creating a set of heating center of masses, wherein the set of heating center of masses are calculated by searching for at least one maximum in the thermal dose distribution; - selecting several sonication points from the multiple sonication points for each member of the set of heating center of masses, wherein the one or more sonication points are selected using a predetermined criterion; - determine a spatially dependent targeting correction by comparing each member of the set of the heating center of masses to the one or more sonication points; and - control the high intensity focused ultrasound system to offset the adjustable focus by the spatially dependent targeting correction. - control the high intensity focused ultrasound system to sequentially sonicate the multiple sonication points to exceed a therapeutic threshold; - control the magnetic resonance imaging system to repeatedly acquire the thermal magnetic resonance imaging data; - repeatedly reconstruct multiple thermal maps using the thermal magnetic resonance imaging data; - determine a time dependent accumulated thermal dose distribution using the multiple thermal maps; - calculate a heating center of mass for each of the multiple thermal maps creating a set of heating center of masses, wherein the set of heating center of masses are calculated by searching for at least one maximum in the thermal dose distribution; - selecting several sonication points from the multiple sonication points for each member of the set of heating center of masses, wherein the one or more sonication points are selected using a predetermined criterion; - determine a spatially dependent targeting correction by comparing each member of the set of the heating center of masses to the one or more sonication points; and - control the high intensity focused ultrasound system to offset the adjustable focus by the spatially dependent targeting correction.