Sound levels daring operation of magnetic resonance imaging systems

Abstract

The sound or noise levels at the patient position in the bore of several different magnetic resonance imaging (MRI) systems were measured. The measurements were conducted with the microphone/preamplifier component connected to the sound-level meter (SLM) with an extension cable so that the SLM was remote from the MRI scan room. Preliminary tests and analyses were conducted to ascertain that the microphone/preamp functioned normally in the strong magnetic field and rf environment. Subsequently, A-weighted, flat-weighted, and octave band noise levels were measured in the MRI system bore areas during a variety of image scanning sequences. The noise levels were in the range 75–95 dB A-wt., and 85–105 dB flat-wt. Greater noise levels tended to be correlated with greater magnetic field strengths and with more rapid and detailed image scanning sequences.