Wardray Premise

RF Shielding for MRI Installations

Part of the Wardray Premise Total Radiation Shielding Package



Wardray Premise are experts in RF and Magnetic Shielding for MRI Rooms. We are the only British manufacturer of RF cages and have completed over 200 installations for all major equipment manufacturers over the last 15 years.

Using a series of purpose-made components produced from the highest quality materials, each cage is designed and manufactured in our modern UK factory to suit the site conditions and satisfy the requirements of each individual contract.

We have also completed a number of modifications to existing MRI Rooms.

In addition to conducting RF tests for our own cages, we are pleased to carry out independent tests on other sites and mobile units.

Relax & View® Ceiling Panels
Relax & View® Ceiling Panels
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CT & MRI for Spire
CT & MRI for Spire
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General Specification

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An all British shielding structure using a unique modular system from a series of purpose made components produced from the highest quality materials. The self supporting aluminium structure is designed, manufactured and installed under our strict quality control.

Each RF cage is produced to suit local site conditions. The rigid construction is easily adapted to overcome late changes in sizes and specification and allows the easy introduction of additional filters.

The finished product exceeds the attenuation levels required by the major equipment manufacturers. Our designs are regularly revised and updated as new scanners are introduced.

The standard thickness of the walls and ceilings is approximately 50mm, excluding any internal finishes. Floor thickness, excluding the final covering but including the 4mm base insulation membrane, is approximately 27mm.

Our cage is produced from a series of single and multiple extruded aluminium tube sections locked together with special brackets to form a rigid frame of walls, ceiling and floor.

The floor frame is infilled with high density boards to give a flush finish. Additional supporting pads for the magnet can be introduced if necessary. The internal surfaces of the frame are lined with aluminium sheet, locked into the threaded groove in the extrusion with a face fixed moulded aluminium cover strip.

This unique system gives a double overlap of the material at each panel joint for the maximum level of performance.

Using a construction formed from one rigid material eliminates any problems of structural stressing and flexing through building movement or varying coefficients of expansion. It also eliminates the inherent weakness of timber framework, thinner shielding materials and the problems associated with some clamping systems.

Construction of Aluminium MRI Cage
Construction of Aluminium MRI Cage
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Double Sealed Joint
Double Sealed Joint
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Why Aluminium?

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Aluminium has a proven record on a worldwide basis for high specification RF facilities used by leading telecommunication companies in sensitive military installations.

It is often the preferred material for high field 3T scanners and for many of the mobile MRI Units now in regular use and subject to the rigours of transportation from site to site.

The specification required to meet the necessary conductivity properties and attenuation levels provides strength, which is put to advantage in the overall room construction.

 

This construction allows for the easy removal and re-fitting of panels to allow magnet access in the event of an equipment upgrade

Sound installation can be incorporated into the framework of the walls during assembly.

RF Testing

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Aware of the advances in technology Wardray Premise have, in conjunction with leading EMC analysts, developed their own ‘in house’ testing facility. Using highly sophisticated RF test equipment, our construction methods have been refined to obtain attenuation levels at the wide range of frequencies now specified by the leading equipment manufacturers. These levels are far in excess of their current requirements which leave us well equipped to produce rooms for higher powered magnets.

RF Cage Construction
RF Cage Construction
 

Upgrading Existing Facilities

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The Wardray Premise cage is particularly suitable for modification when equipment is upgraded.

An RF test is undertaken to confirm acceptable attenuation levels and our work can include providing new filter panel frames, floor supports etc. to meet the requirements of the new equipment. This work can also include the installation of an emergency venting panel within the door (as illustrated).

Room Fit Out

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We work in close co-operation with site contractors involved in the installation of air conditioning, power, lighting and internal finishes. Alternatively we can contract to provide a complete installation to final fit out stage (working with our sub contractors).

Guarantee

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The main structure is based on the use of high grade aluminium which will not degrade beyond our stated design limits.

A five year guarantee is offered for attenuation performance, defective materials and workmanship on the enclosure (excluding moving parts and finger strips).

As a result of continuing development and improvements we reserve the right to change the specification without prior notice.

Important Notes

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Post-installation care to preserve the validity of the guarantee.

The RF cabin must be protected against water ingress, either from external weather penetration or leakage from internal services.

At no time must any item be fixed to the cage or any penetrations passed into the room other than as authorised through the manufacturer’s pen panel.

Any proposed works involving the cabin structure must not be undertaken without first seeking our advice and written consent.

 Installation
Relax & View® Installation
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Door Sets

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These are constructed with an aluminium facing which can be finished in a choice of veneers, laminates etc. with matching timber lippings.

Adjustable, purpose made lift off hinges are provided and plated beryllium copper finger strips are fitted to the door frame (jambs and head) to minimise wear and tear.

Finger strips are also fitted to the bottom edge of the door to provide contact with the low contour threshold, which are easily replaced in the event of damage or wear.

The standard single leaf door size gives a clear opening 1200mm wide x 2100mm high.

Doors and framework incorporate acoustic seals to jambs, head and bottom edge of door. In addition, a continuous membrane throughout the door provides excellent acoustic attenuation properties.

The locking mechanism consists of a single latching multipoint Euro-cylinderlock.

Lifting the handle engages two further retaining bolts to ensure maximum contact.

Emergency Venting Panel

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This panel providing an aperture 600mm x 600mm includes an inbuilt resistance to prevent the panel accidentally closing during an emergency venting procedure.

It is normally 'factory fitted' into a door during an initial installation but a 'retro-fit' option is available on request

MRI Doorset
MRI Doorset
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MRI Door With Emergency Venting Panel
MRI Door With Emergency Venting Panel
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Observation Windows

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These consist of two pieces of glass, each containing a thin layer of blackened copper mesh with an anti-reflective coating. They are glazed and laminated to form a complete window unit which is integrated into an aluminium frame.

The space between the two window sections gives enhanced RF and sound attenuation and is designed to eliminate moiré fringes.

Our standard window sizes are shown in the table on the right.

MRI Observation Window
MRI Observation Window
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Standard Window Sizes
Width Height
1200mm 900mm
1500mm 900mm
1800mm 900mm

Filters and Wave Guides

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Air Conditioning Filters

All air conditioning must enter and leave the cage through suitably approved RF filters. These are available in several stock sizes.

Galvanic separation is achieved by the inclusion of a timber frame fitted on the outside of the cage. A separate equalizing vent filter is fitted (usually above the door) to alleviate any vacuum effect within the room.

Electrical Filters

Filters are available with either 5 amp or 25amp rating.

They are provided for connection to any supplementary electrical equipment used within the room that cannot be routed through the manufacturers' service panel.

Open Wave Guides

These consist of access tubes in varying diameters and lengths, are easily installed and preserve the integrity of the shield.

Medical Gas Filters

These are engineered to meet medical gas standard HTM 02-01. Constructed with anti-static connections, they have been pressure tested for 1.5 hours at a maintained pressure of 150psi.

Service Panel Frames and Quench Pipe Filters

These are produced to suit individual manufacturers’ specifications.

Any specific requirements for floor supports for the magnet and/or ducting within the flooring for services can also be included.

Honeycomb Filter for Air Conditioning, etc.
Honeycomb Filter for
Air Conditioning, etc.
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Electrical Filters
Electrical Filters
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Open Wave Guide
Open Wave Guide
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Medical Gas Filters
Medical Gas Filters
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Magnetic Shielding

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The addition of magnetic shielding to MR suites will depend on the type of MRI equipment and the location of the site.

If the proposed location of the scanner allows the 0.5 gauss line of the magnetic field to extend outside the room this can have serious implications; affecting members of the public with implants or pacemakers, Causing disturbance to TV’s, computer monitors, ultrasound scanners, etc.

In addition, interference to the operation of the MR scanner may be caused by traffic, lift shafts or any other moving object with a high level of ferrous magnetic metals.

In both instances, unless the room can be re-located, magnetic shielding is the only option. The need for this will be based on the position of the magnet within the room and the areas outside to be shielded.

The introduction of a ferrous metal with a high permeability will contain the magnetic field (e.g. galvanised, low carbon or silicone steel) by distorting the magnetic field.

This may cause the gauss line to extend outside another part of the room. Therefore it is necessary to undertake a complete survey using a range of multiple finite element calculations to achieve an optimum shielding performance.

This simulation will identify the thickness of the material to be used and the extent of the shielding required in specified wall, ceiling and floor areas.

We would be pleased to provide a full survey, complete specification and quotation for the supply and installation of this work on request.

To undertake this survey it is necessary to provide full details of the proposed room layout from the equipment manufacturer, together with details of the host room and its relative position to the surrounding facilities.

Click image to enlarge
Click image to enlarge

Enquiry Guide: RF Cages

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To help us provide an accurate quotation, please supply the following information with your enquiry:

  • If available, please provide a drawing or dimensioned sketch.
  • Door finish: does it open into or out of the room?
  • Proposed equipment manufacturer if known and type of equipment, model number etc including site planning guide.
  • Types and quantities of any special filters required.
  • Window size
  • Requirement for magnetic shielding.