A device for treatment of a tissue of a living being, the device including: - a transducer for emitting a beam of ultrasound waves, preferably high intensity focused ultrasound waves, for irradiating the tissue, the beam being focused on or focusable onto a focal point, the transducer being mounted on a movable treatment head; - an ultrasonic imaging device (2, 3) mounted on the treatment head having an imaging plane intersecting the focal point (f); - a control unit for controlling the movement and position of the treatment head and the operation of the transducer and the imaging device (2, 3); wherein the treatment head is adjustable to a treatment position and a monitoring position, wherein in the monitoring position the distance between the transducer and the tissue is smaller than in the treatment position, wherein the control unit is adapted to trigger the transducer to emit at least one beam of ultrasound waves when the treatment head is in the treatment position, and perform imaging of an area surrounding the tissue at least when the treatment head is in the monitoring position, and characterized in that the device includes an inflatable balloon surrounding at least partially the treatment head, adapted to contain or containing a coupling fluid and defining a contact surface of the treatment head, wherein the control unit is adapted to raise the pressure in the balloon when the treatment head is in the treatment position and lower the pressure in the balloon when the treatment head is in the monitoring position. - a transducer for emitting a beam of ultrasound waves, preferably high intensity focused ultrasound waves, for irradiating the tissue, the beam being focused on or focusable onto a focal point, the transducer being mounted on a movable treatment head; - an ultrasonic imaging device (2, 3) mounted on the treatment head having an imaging plane intersecting the focal point (f); - a control unit for controlling the movement and position of the treatment head and the operation of the transducer and the imaging device (2, 3); wherein the treatment head is adjustable to a treatment position and a monitoring position, wherein in the monitoring position the distance between the transducer and the tissue is smaller than in the treatment position, wherein the control unit is adapted to trigger the transducer to emit at least one beam of ultrasound waves when the treatment head is in the treatment position, and perform imaging of an area surrounding the tissue at least when the treatment head is in the monitoring position, and characterized in that the device includes an inflatable balloon surrounding at least partially the treatment head, adapted to contain or containing a coupling fluid and defining a contact surface of the treatment head, wherein the control unit is adapted to raise the pressure in the balloon when the treatment head is in the treatment position and lower the pressure in the balloon when the treatment head is in the monitoring position. trigger the transducer to emit at least one beam of ultrasound waves when the treatment head is in the treatment position, and perform imaging of an area surrounding the tissue at least when the treatment head is in the monitoring position, and characterized in that the device includes an inflatable balloon surrounding at least partially the treatment head, adapted to contain or containing a coupling fluid and defining a contact surface of the treatment head, wherein the control unit is adapted to raise the pressure in the balloon when the treatment head is in the treatment position and lower the pressure in the balloon when the treatment head is in the monitoring position.