Measurement of equivalent continuous A-weighted sound pressure level of driving sound of three tesla MRI equipment

Magnetic resonance imaging (MRI) equipment is important in medical diagnosis. The equipment utilizes a technology of tomography by the nuclear magnetic resonance phenomenon for imaging. Driving sound of MRI equipment is loud and it is caused by using the gradient magnetic field controlled by imaging sequence. It generates loud sound which depends on imaging sequence. The sound pressure level of the driving sound is over 100 dB sometimes and it makes the ear-protector necessary. There are some researches of the driving sound. In this paper, this paper shows the measurement result of equivalent continuous A-weighted sound pressure level of distribution in the three tesla MRI equipment which is Philip Achieva 3.0T X-series. Number of measurement point is 21 on the table; the 15 points located inside of the bore and the 6 points located outside of the bore. Imaging sequences of the measurement sound are slice positioning, T2 weighted imaging (T2W) and Echo planar imaging (EPI). The measurement data length is 30.04 seconds. The result showed that the driving sound of each imaging sequences on the table was loud. The maximum equivalent continuous A-weighted sound pressure level (LAeq) of slice positioning, T2W and EPI were 114.7 dB, 106.0 dB, 114.3 dB respectively. These values were larger than driving sound of 1.5 tesla MRI equipment. The maximum value of instantaneous sound pressure was 123.9 dB in the three sequences of the 3 tesla MRI equipment. So, it shows the instantaneous value is important parameter.