RF Shielding


Interference from magnetic fields can be an exclusion criterion in choosing a location for an MRI system.

More about B0-measurements

Trams, subways, parked or moving trucks and cars, lifts or the change of magnetic field conditions, according to the distance to the location of an MRI, may be the reason that a location is not suitable. Power lines or power cables may also generate large magnetic fringe fields which can have a big impact on the MRI. inmed measures and documents the existing magnetic influences at a location in 3 layers over a period of at least 24 hours. Based on the acquired data, inmed can determine the electromagnetic compatibility of a site. By mounting adequate magnetic shielding, the magnetic effects are attenuated, so that thereafter at a location that had failed the first B0-measurement can be made suitable for an MRI installation.

Sound Propagation

In principle, noise can be divided into structurally-borne sound and airborne sound. Thereby a different approach to eliminate the sound propagation must be considered.

More about Sound Propagation

The sound propagation within a room or building (structurally-borne sound and airborne sound) depends on local circumstances – this means the structure of the rooms and the structure of walls, ceilings and floors. The fixing points of the magnet, penetrations and penetration panel, RF-doors, RF-windows and the interior finishing inside of a RF-shielded enclosure are the most critical components.

Sound damping

The standard cage achieves a sound damping of >40db.

Measures for optimized sound damping:
Sound damping for airborne sound with additional partition walls, sound absorbing heavy curtains, additional sound absorbing ceilings, sound absorbing wall and cabin floor construction, RF-door and RF-window in sound damping version.
Sound damping for structurally-borne sound with uncoupling of the magnet from the building and introduction of additional mass.

The following sound damping measures have proved themselves:

Cabin floor:

  1. Fixation of the magnet on separate stand, floatingly mounted RF-cage, floor floatingly mounted on sound and shock absorbing under layer
  2. Introduction of additional mass (chipboard plates) etc.

Cabin walls:

  1. Increase of mass (chipboard plates, gypsum boards)
  2. Additional lining with sound absorption material
  3. Additional wall with sound absorption materials
  4. Cabin walls sealed to cabin ceiling

Cabin ceiling:

  1. Self-supporting ceiling construction
  2. Insertion of noise insulation material
  3. Maintaining ceiling distances
  4. Increase of mass (chipboard plates, gypsum plates or lead)
  5. Insertion of membranes, executed with lead-covered hardwood boards

All specifications referring to the noise level include the building structure. A noise absorption for the floor of 60 dB (A) consists of the raw floor structure, the insulation materials and the floor structure of the RF-shielding.

Magnetic Shielding

After completion of a site visit and site evaluation, the results of a B0-measurement may show that an MRI system can be installed only after an additional magnetic shielding is provided.

More about Magnetic Shielding

The environmental conditions in the surrounding of an MRI system must be free of interfering influences. Magnetic shielding achieves a safe use of an MRI system any hazard to patients and staff and reduce in the reverse case the influences of moving ferromagnetic parts in the vicinity of the magnet (elevators, cars or trucks) on an MRI system magnet. Therefore magnetic shielding is an important measurement for the planning and realization of an MRI project. An MRI site, which is inappropriate without a magnetic shielding, can be converted to meet the given specification of an MRI manufacturer after the installation of proper magnetic shielding. Magnetic shielding is made of soft iron plates or transformer plates. After completion of the installation of a magnetic shielding, the position of the fringe field lines are measured and documented. For special requirements (trains and subways nearby) active field compensation may be required, which can be provided as well.

All work in connection with an RF-shield or magnetic shielding enclosure is conducted by our partner companies HAMACO and ALBATROSS.