A high-intensity focused ultrasound therapy unit (12), in particular for ultrasound ablation treatment, comprising an ultrasound transducer probe (40) with an ultrasound transducer array (44), a guiding unit (38) that is configured for monitoring a position of the ultrasound transducer array (44) relative to a subject of interest (24), and for providing information on the monitored position to a human interface, and a control unit (42) that is configured to control at least one operational parameter of the ultrasound transducer array (44), so as to adjust the penetration depth of the focused ultrasound beam into the subjects tissue depending on a rate of change of a relative position of the ultrasound transducer array (44) relative to the subject of interest (24) and—a magnetic resonance image-guided high-intensity focused ultrasound therapy system (10), comprising a high-intensity focused ultrasound therapy unit (12) and a magnetic resonance imaging system (14) as the guiding unit (38).
