A therapy system comprises a therapy module to direct a therapeutic action to a target along successive trajectories in a target region that includes the target. A thermometry module is provided to measure temperature a measurement field and in particular to compute a thermal dose. A control module to controls the therapy module to apply the therapeutic action along the respective trajectories on the basis of the measured temperature and/or thermal dose. The successive trajectories are located in the target zone outward or inward relative to one another within the target zone. In particular the therapeutic action subsists in application a focused ultrasound beam to the target. Temperature measurement is done on the basis of magnetic resonance signals.
