VIEWRAY MRIdian System 4.5 - Risks of Non-MR Safe Monitoring and Interventional Devices; Hazardous Noise Levels

Chapter 2: Safety Information and Alerts
50 MRIdian® system L-0009 Release 4.5 ViewRay Inc.
2.14 Risks of Non-MR Safe Monitoring and Inter-
ventional Devices
Non-MR safe patient monitoring devices may measure erroneous
values because of RF field interference.
 Use only MR-safe vital parameter measurement devices for monitoring. Only equipment
labeled as MR-safe by its manufacturer should be used with the MRIdian® system.

Ensure any ECG electrodes and leads are labeled as MR-safe by the manufacturer
and that they have not passed their expiration date.
 Ensure any interventional device used has shielded electronics to reduce
interference with MR signal.
 Follow your facility's protocol for monitoring sedated or unconscious patients.
These patients are unable to alert operators of excessive heating and associated
tissue damage so they must be monitored closely.
2.15 Hazardous Noise Levels
The MRIdian® system generates substantial acoustic noise in the
treatment room during treatment. Temporary or permanent
hearing
loss can occur if adequate hearing protection is not used.
The recommendations below are based on measurements made on the MRIdian MRIS in the
mode pr
oducing the worst case clinical scan conditions [ISO 1999.] The logarithmic decibel
scale, dB, is used when describing sound power. Sound levels are designated by an A
indicating the sound was measured on the A scale of a standard sound level meter at slow
response. The FDA released updated guidelines for acoustic noise levels associated with the
operation of MR systems, on July 14, 2003, as follows: a MR device should not produce noise
having a peak unweighted sound pressure level greater than 140 dB, or A-weighted root
mean square (rms) sound pressure level greater than 99dBA with hearing protection in place.
 Inf
orm patients about the noise generated during treatment.