Shadowless lights using Light Emitting Diode (LED) have been widely introduced in surgical operation rooms. LED lighting devices contain a switching power supply, but they may cause electromagnetic interference (EMI) with wireless communications. In the surgery, EMI with electromagnetic navigation systems (EMNS) was reported. Then, we investigated the effects of using LED shadowless lights on the EM environment around an EMNS. Most of the magnetic fields intensities radiated from the LED shadowless lights not exceeded the background noise at a distance over 1 m. But that were higher than that in the near field. EMI with the EMNS by the magnetic field radiated from the LED shadowless light was not observed. An EMNS enables to locate surgical instrument to be tracked using EM field radiated from emitter. The maximum magnetic field intensity of the EM emitter was 140 dBµA/m at a distance of 10 cm. LED shadowless lights are generally used in the operative field at a distance of 1 m. The maximum intensity of the magnetic field radiated from LED shadowless lights was less than that of the EM emitter. Therefore, we concluded that LED shadowless lights will rarely interference with EMNSs.
