Bruker BioSpec 117 AVANCE III, Руководство пользователя

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Laboratory infrastructure and interactions
Limit values of magnetic disturbances
Limit values of magnetic disturbances
Table 5.1: Limit values of magnetic disturbances
5.3.1.3 Effect of MR system to other equipment
The stray field of the MR system can lead to sustained disturbance of sensitive equipment in the
vicinity of the system and to irreversible damage.
The following table gives threshold values on acceptable disturbance of some equipment. Be-
fore using equipment in the stray field of the magnet, check the acceptable fields in the manual
or consult the manufacturer of the equipment.
Interference fields of equipment
Interference fields of equipment
Table 5.2: Interference fields of equipment
5.3.1.4 Remote magnetic effects
The magnetic field of the MR system interacts with ferromagnetic materials built into the build-
ing. The interaction leads to magnetization of the ferromagnetic materials, which in turn may
lead to an unexpected higher local magnetic field strength at distant sites.
A check must therefore be made as to whether there are ferromagnetic structures at the mag-
net's installation site, which may lead to the aforementioned effects at distant sites. If such struc-
tures exist, these areas must be measured, labeled or shielded separately after the magnet has
been installed.
Minimum distance
[m]
Reference stray field
strength
[mT]
Mobile sources of magnetic dis-
turbance
0 0.5 ferromagnetic objects < 1 kg
0 0.1 ferromagnetic objects < 25 kg
2 0.1 ferromagnetic objects < 250 kg
4 0.1 ferromagnetic objects < 500 kg
6 0.1 ferromagnetic objects < 5000 kg
9 0.1 ferromagnetic objects > 5000 kg
40 0.1 subways, trucks, trains
Disturbance lev-
el (mT)
Equipment and systems
5 MR system electronics
3 Electric motors, cameras, mechanical clocks
1 Hard drives and mobile data media, credit cards, oscilloscopes
0.5 Medical implants, pacemakers, insulin pumps, neurostimulators, X-ray
equipment
0.3 Ultrasound equipment, video cameras
0.2 CT scanners
0.1 CRT monitors, particle accelerators, electron microscopes, mass spec-
trometers, EEG equipment
0.05 X-ray image intensifier, gamma cameras