The invention may improve measurement quality of sensor by placing them at the optimal position. The invention is directed to a sensor positioning system (1) for positioning and placement of a sensor arrangement on a patient's body. The sensor positioning system (1) comprises a sensor arrangement (10) comprising a first sensor (11) and a second sensor (12), a placement tracker (20), and a processor (30). The placement tracker (20) is configured to track a position and/or orientation of the second sensor (12) relative to the first sensor (11) to determine an actual position and/or orientation of the second sensor (12) on the patient's body (2). The processor (30) is configured to compare the actual position and/or orientation of the second sensor (12) with a desired position and/or orientation of the second sensor (12) and to generate an output signal (35) indicating a difference between the actual position and/or orientation of the second sensor (12) and the desired position and/or orientation of the second sensor (12).
