In a medical apparatus including a medical imaging system and a medical position and navigation system (MPS), the medical imaging system including an imaging transmitter, periodically emitting imaging radiation and an imaging detector, the medical position and navigation system including at least one MPS transmitter periodically transmitting MPS radiation and at least one MPS detector, the MPS radiation electromagnetically interfering with at least one mode of operation of the imaging detector, a device for eliminating interference to the imaging detector caused by positioning radiation, the device comprising a synchronizer, coupled with the medical imaging system and with the medical position and navigation system, synchronizing the imaging detector and each the at least one MPS transmitter, so that neither of the at least one MPS transmitter transmits during the at least one mode of operation of the imaging detector.