Sound source measurement of magnetic resonance imaging acoustical noise for feedforward active noise control system

We proposed the Active Noise Control (ANC) system reduce the loud MRI sound. It was important for performance improvement of the system. Therefore we estimated the sound source of MRI acoustical noise. The position of the sound source of MRI acoustical noise was between the center and the edge in the gantry of MRI equipment. MRI equipment is important for the medical inspection which gets the tomography of the body without X-ray. The patient of the MRI inspection needs to use the ear protector because the MRI equipment generated the loud sound which the sound pressure level was around 100dB. The study considers improvements to the acoustical environment when using the ANC system for MRI patient. The ANC system we developed is a feedforward system MRI acoustical noise is unsteady and pulsed. The system uses non-magnetic devices ear protectors, and optical microphones, because the MRI rooms are highly magnetic environments. We determined the sound source of MRI acoustical noise to set the reference microphone. In this case, it was shown that th e reduction effect of the ANC system for acoustical noise by the computer simulation. As a result, the system reduced the MRI acoustical noise by around 50dB.