Extracorporeal shock wave lithotripsy system comprising: a camera for capturing images of visual references, the camera being arranged on a trolley which is freely movable, a patient table having a first mounting rail along a first longitudinal side of the patient table and a second mounting rail along a second longitudinal side of the patient table, the second longitudinal side being opposite to the first longitudinal side, a first visual reference being arranged on the first mounting rail or the first longitudinal side and a second visual reference being arranged on the second mounting rail or the second longitudinal side, an ultrasound transducer for examining and imaging a body part comprising an object, in particular a stone, of a patient, the ultrasound transducer having a third visual reference, a therapy source for treating the body part of the patient, the therapy source comprising a fourth visual reference and a shock wave source having a focal zone for destroying the stone, a displacing means for changing a relative position of the patient table and/or the therapy source, a measurement and evaluation system connected to the ultrasound transducer, the camera, the therapy source, and the displacing means, the measurement and evaluation system inter alia being adapted to evaluate relative positions between at least two of the ultrasound transducer, the therapy source, the first mounting rail and the second mounting rail, a display connected to the measurement and evaluation system for displaying a relative position of at least the body part and a position of the focal zone of the therapy source wherein the ultrasound transducer is mountable to the patient table for treatment of the patient, wherein the ultrasound transducer is freely adjustable in space and lockable in a desired position and orientation wherein the measurement and evaluation system and/or the display comprise a graphical user interface for inter alia displaying a positional relationship, in particular an overlay, of the focal zone of the therapy source and the ultrasound plane generated by the ultrasound transducer wherein the graphical user interface is adapted to show a detection region being the region wherein a visual reference may be detected by the camera of at least one of the first visual reference, the second visual reference, the third visual reference and the fourth visual reference, wherein the graphical user interface is adapted to show a detection region of the third visual reference and the fourth visual reference. a camera for capturing images of visual references, the camera being arranged on a trolley which is freely movable, a patient table having a first mounting rail along a first longitudinal side of the patient table and a second mounting rail along a second longitudinal side of the patient table, the second longitudinal side being opposite to the first longitudinal side, a first visual reference being arranged on the first mounting rail or the first longitudinal side and a second visual reference being arranged on the second mounting rail or the second longitudinal side, an ultrasound transducer for examining and imaging a body part comprising an object, in particular a stone, of a patient, the ultrasound transducer having a third visual reference, a therapy source for treating the body part of the patient, the therapy source comprising a fourth visual reference and a shock wave source having a focal zone for destroying the stone, a displacing means for changing a relative position of the patient table and/or the therapy source, a measurement and evaluation system connected to the ultrasound transducer, the camera, the therapy source, and the displacing means, the measurement and evaluation system inter alia being adapted to evaluate relative positions between at least two of the ultrasound transducer, the therapy source, the first mounting rail and the second mounting rail, a display connected to the measurement and evaluation system for displaying a relative position of at least the body part and a position of the focal zone of the therapy source wherein the ultrasound transducer is mountable to the patient table for treatment of the patient, wherein the ultrasound transducer is freely adjustable in space and lockable in a desired position and orientation wherein the measurement and evaluation system and/or the display comprise a graphical user interface for inter alia displaying a positional relationship, in particular an overlay, of the focal zone of the therapy source and the ultrasound plane generated by the ultrasound transducer wherein the graphical user interface is adapted to show a detection region being the region wherein a visual reference may be detected by the camera of at least one of the first visual reference, the second visual reference, the third visual reference and the fourth visual reference, wherein the graphical user interface is adapted to show a detection region of the third visual reference and the fourth visual reference.