Table 3-1: Steel Mass Limits to Magnet Isocenter
Limits Of Steel Mass lbs/ft
2
(kg/m
2
)
Distance From Magnet Isocenter in. (mm)
Distance Below Top Surface Of Floor in.
(mm)
0 (0)
0-45 (0-1143)
0-3 (0-76)
2 (9.8)
45-47 (1143-1194)
3-5 (76-127)
3 (14.7)
47-52 (1194-1321)
5-10 (127-254)
8 (39.2)
52-55 (1321-1397)
10-13 (254-330)
20 (98.0)
55+ (1397+)
13+ (330+)
2.3 Vibration Requirements
Excessive vibration can affect MR image quality. Vibration testing must be performed early in
the site planning process to ensure vibration is minimized. Both steady state vibration (exhaust
fans, air conditioners, pumps, etc.) and transient vibrations (traffic, pedestrians, door slamming,
etc.) must be assessed (see
). Specific requirements for vibration mitigation,
include:
1. The Magnet (MAG) cannot be directly isolated from vibration. Any vibration issue must be
resolved at the source
2. MR Suite HVAC must have vibration isolation
3. A vibration analysis must be performed at the proposed site with the results (and any
mitigation) forwarded to the GE Healthcare Project Manager of Installation (PMI). See the
Chapter 7, MR Site Vibration Test Guidelines
4. A transient vibration test must only be performed after a steady-state test has been
performed and all steady-state sources of vibration have been mitigated
5. Transient vibration levels above the specified limits in the
Chapter 7, MR Site Vibration Test
6. Any transient vibration that causes vibration to exceed the steady-state level must be
mitigated
7. Vibration test consultant must account for non-mechanically induced signals such as
equipment instabilities, thermal drift or RF interference
SIGNA Voyager Pre-Installation
Direction 5680008–1EN, Revision 2
62
2 Magnet Room Structural Requirements