This report originally appeared in the January 2009 issue of DOTmed Business News.

When Ken Poteete was the CEO for Georgetown Healthcare System, the health care provider upgraded from a .5T to a 1.5T. Even though the equipment was upgraded, there were still problems. "When the install was complete, some of the protocols produced poor image quality," says Poteete. "After two weeks of troubleshooting, it turned out there was a breach in the RF shield."

There are many questions that need to be answered and decisions to be made when it's time to design a shield. All MRI's need RF shielding but the need for magnetic shielding is a function of magnet location with respect to uncontrolled or public areas. The decision to include magnetic shielding is one of the most important, especially when it comes to cost. The use of annealed steel plate or silicon steel, in a very specific geometry, is required to capture and contain the magnetic field.

"There's often confusion in shielding among general contractors. I have to explain that there is a difference between RF shielding and magnetic shielding," says Mike Profeta, President of Magnetic Resonance Technologies Inc. "RF shielding prevents exterior radio frequencies from getting to the MRI system in order to keep interference or artifacts out of the images. Magnetic shielding is required most frequently when the system's 5 gauss magnetic field extends into uncontrolled areas and needs to be captured."

Joseph Thompson, owner of Assured Imaging Services, says, "Interference of various kinds of waves can lead to distorted images, so every MRI suite should have proper shielding to produce quality images."

For those using the low powered Tesla magnets, there's no need to worry about what's ahead.

"Many customers are getting 1.5T or an open magnet, and looking ahead to what needs to be changed when they upgrade to a 3T, but quite often there really isn't anything else they need to do," says Ben Turner, Vice President of Sales and Marketing, ETS-Lindgren. "Most shields that are suitable for 1.5 are also suitable for 3T. That's something the end user needs to be aware of. They could be hit with an additional cost when nothing is really being added."

Material Choices

A number of materials are utilized for MRI shielding as companies make use of aluminum, galvanized steel and conductive copper to isolate the system from disturbances. Each company has its own spin on what's best for a room.

According to Marc Holder, Operations Manager of Global Partners in Shielding, Inc, you can basically use any conductive material to do RF shielding and each has its own merits.

"Aluminum has a short life so it's ok for a couple of years but anything past that, it oxidizes and starts leaking," Holder says. "Copper is very good but really the price of copper is astronomical and you need a substructure to support copper foil. The galvanized panel system that most of the companies use is very good because it tends to be free standing and very durable. It's a very hard, solid product, so it stands up by itself. With steel you do get a small amount of magnetic shielding for free and you can generally see an improvement in image quality when you use steel over copper or aluminum."

Profeta explains that apart from some nice innovations with RF doors, there hasn't been that much advancement in the RF shields themselves; it's just the different construction companies use. Some shielding companies have added other products to augment shield offerings such as metal detectors at the doorway, and panoramic lights above the patient couch.




"We offer soldered seamed copper rooms as a first choice for the customer that is interested in the best. We flash all the openings with a heavy weight copper, which adds quality and long term reliability," he says. "Many companies out there are using bolted together copper panels or galvanized metal panels that are bolted together. We also offer a galvanized panel system. When dealing with a reputable company, all these systems will work, but nothing beats the long term reliability and versatility of soldered copper."

Profeta says he always avoids aluminum as it is not reliable long-term.

For Med Design Inc., copper is almost always recommended for customers looking at shielding options.

"I have my own twist on what I do that makes the rooms unique," says Med Design President Gregory Vojak. "We like to do copper rooms. We use a cement backboard floor system rather than plywood and that makes it much sturdier."

The OEM that manufactured the MRI provides performance specifications for the room in terms of allowable measurements for RF or magnetic readings. However, it's often left to the contractors, such as independent service companies that specialize in MRI shielding to determine the best materials and design approach.

"One of the old ways of doing it is having a wood start frame system built and having copper sheets stapled or nailed to it and joints soldered, which is the most time consuming way of installing a shield, but it also gives you your tightest shield and your best attenuation. Many prefer to have that system if they are using 3T magnets for research" says Lou Campedelli, MRI Shielding Project Manager for NELCO. "One of the major advancements has been using a panelized system with a clamping system compression type fitting to join the panels. It's an economical shield and one that's considered modular so you could disassemble it much easier than a soldered system and it lends itself well to magnet change-outs."

Anything that penetrates the shield requires additional attention: special RF filtering for electrical wiring, waveguides for pipes, and specialized honeycomb material or waveguides for air vents. The MRI suite also requires shielding a pipe for the helium exhaust penetration along with specially designed doors and windows.


Magnetic Shielding

If required, magnetic shielding is utilized to protect the area around the MRI room and that will add time and cost to the project since it uses steel to contain the magnetic fields.

"Low carbon steel is the best metal if you will be placing the material in a very strong magnetic field," Lindgren's Turner says. "For example, look at the magnetic plots of the MRI you are purchasing, approximately what gauss level lies at the wall where your magnetic shield will be placed? In general, I would say if the field is 30 gauss or higher, you may want to use low carbon steel. If that gauss level is less than 30 gauss, you may want to use a grade of silicon steel."

Turner explains that there are two basic reasons for magnetic shielding. It is needed when the proposed location of the MRI system allows the magnetic field of the MRI system to extend beyond the MRI scan room itself and into surrounding areas that could be adversely affected by the magnetic field from the system.

A typical example would be an MRI system that generates a 5 gauss field that extends into a public area. Magnetic shielding is also needed when the proposed location of the MRI system might cause it to be adversely affected by something around the MRI suite.

For instance, an MRI system placed in close proximity to roads could make its operation less than ideal since automobiles are made of ferrous magnetic metals. These metals can negatively impact the quality of images generated by an MRI system when they operate too close to large moving metal objects.

"There are two principle properties that one considers when choosing what type of metal to use for a magnetic shield, permeability and saturation," Turner says. "Permeability is the ability of the metal to attract magnetic field to it. Saturation is the ability of the metal to absorb magnetic field within its wall."

Shielding vendors also understand that MRI equipment has to be shielded from any local environment interference, such as computers, other medical equipment and appliances which may emit radio frequency signals disturbing MRI measurement. The local environment has to be shielded from RF and magnetic interference, as strong magnetic fields can mechanically damage sensitive instruments, discharge batteries, or erase magnetic media.

In this respect, the role of the shielding vendor has evolved into more of a problem solver.

"One other thing that comes into play in higher field magnets is the impact the magnets have on the environment," says Michael Krachon, Director of US Division and GM of IMEDCO. "The shielding guys provide some solutions or methods of preventing this device from affecting the rest of the building."

Money Matters

When it comes to the cost of installing a shield, there are many variables that need to be considered. What is the size of the room? What material will you be using? Do you need magnetic shielding? Is there a union requirement for a union? Is there some state regulatory body (like ACA in Florida) that needs to be involved?

"All these factors can add significant amounts of money and time," Turner says. "You can see an RF shield as low as $26,000 for shielding extremity magnets where the room is small. Or you can see a shield approach $500,000 for operative suites, where it's a couple of rooms connected with tons of RF filters and things of that nature."


Current State of the Business

Despite what's happening with today's economy, the shielding industry remains strong. Although many companies reported a drop in activity during the summer months, most are reporting overall year-to-year increases for 2008 as thousands of new shields are expected to be installed.

"There was a lull during the election process, but people are starting to make decisions again," says Vojak. "I'm very busy with more activity than I had last year."

Krachon says since the OEMs are still pushing new MRI technology and encouraging end users to upgrade to the latest and greatest, business is booming.

"Whatever they end up promoting, when they are successful, they need arrangements for a shield so for us, opportunities are out there," he says. "I don't sense any downturn. People are looking carefully, but I would represent that our business has been quite steady."

Still, there are some negative factors affecting the industry. Clinics seem to have less money, reimbursement issues still abound and the cost of material is high.

"The London metals exchange is checked constantly for the commodity pricing on copper, lead and steel," says Campedelli. "We buy a lot of that material every month and the last couple of years the price has been sky high."

The prices have been dropping over the last six months, but staying competitive with pricing will almost always come down to material costs.

"Right now our dilemma is that we have seen an increase in material delivery charges and materials have gone up a great deal. Everyone thinks they should be paying less for shielding but our costs have increased," says Mark Holder, Operations Manager of Global Partners in Shielding, Inc. "Everyone is looking to cut corners but when it comes to shielding, it's not something you can do. You have to do the walls, the floor and ceiling to do the job."

According to Turner, since everyone is dealing with material costs, a company should differentiate themselves from the competition by offering other value-added services outside of just the installation service.


New Challenges

One of the biggest challenges through the years occurred when MRI machines started moving from the corner ground floors to other levels, which created some shielding problems with structure and cost. But solutions came and for the most part, companies can design a proper MRI shield for just about any MRI room.

"Shielding over time, has dealt with things that we hadn't thought of before but then it came into play and solutions were developed," Thompson said. "With shielding, pretty much wherever you need it now, you can do it."

Over the last few years, new challenges have popped up concerning safety issues.

"What we're seeing now is a requirement to have the door swing to the outside," says Profeta. "We have also seen more strict and stringent requirements on the vent piping for the magnet. In the event that the magnet venting system fails, you do not want the room to pressurize and keep the door from opening. In every new installation when given an option, they prefer to have the door swing out and it's something that needs to be considered with every new design."

The challenge with the door concerns space, since now you need to capture the square footage outside the box for the door swing. If you have to have the door swing in, you can add a pop-out hatch-a safety hatch-that will open in the event of a pressurized condition but that too adds cost.

"In some cases now, with the existing rooms, manufacturers have gone back and inspected the venting of the cryogen gas finding deficiencies in existing conditions that they have customers remedy," Profeta says. "We have been contacted by a lot of sites where they have to replace the vent pipe systems because they were improperly installed. Where the door opens inward, they want us to also add a pressure relief vent in the wall or ceiling. This is all relatively new and I agree with this emphasis on safety."

This safety feature can literally be a lifesaver in the event of a magnet quench coupled with faulty or malfunctioning vent pipe system. A quench causes the magnet to quickly heat up and leads to a complete discharge of helium. At best, it can be a costly problem, causing a loss of liquid helium and significant time and money to bring the magnet back to field. At worst, it can release a cloud of cold helium gas that can prove deadly to anyone unable to quickly leave the room.

Common Problems

When properly shielded, an RF room can almost be comparable to an airtight room, but every time you open and close the door-almost like a compression with a vacuum-what happens is that staples and joints start to weaken and other problems develop.

Once the scanner is up and running you may see what is called artifact or noise on the screen across the image. A good MRI tech will be able to tell you what frequency those artifacts are at and can see the degradation of image quality over time.

"There are three basic types of problems that cause this," Turner explains. "The first is simple RF leakage, which is usually not a difficult thing to find. It may be inconvenient in that you may have to tear down drywall to get to the shield to fix it but all in all, this is the least problematic."

This often occurs because outside contractors come and violate the wall by adding wires, phone lines or lights by drilling through the shield. When this happens, the scans will be as bad as if someone left the door open.

"We just checked one in Bakersfield where they changed ownership and they put in an alarm system and the guy didn't realize what an RF room really was," Vojak says. "They drilled a hole in it causing leaks so we fixed that. While we were there we noticed the door was out of alignment and the finger stocks weren't meeting properly so we cleaned and realigned the door as well."

Another problem concerns the magnetic field. Turner explains you may have equipment up the hall or below the MRI suite that hasn't been functioning properly and it's because the MRI magnetic field is sticking out further than it should be.

"Fixing magnetic shielding problems can be very expensive and result in work done around the MRI room," Turner says. "You don't usually shut down the magnet and pull it out and redo the room; you are going to figure out how to fix the problem outside of the MRI room on the walls or ceiling."

A third problem concerns ground isolation issues, which can occur due to moisture on the floor or a leaky room. These can be difficult to find and if they reside in your floor, you will have to shut the magnet down and move it around within the room while you fix other portions of the floor or pull it out entirely - both very costly and time-consuming fixes.

"When they start to see a change in the quality of the images, the technician should be able to tell right away if there is an RF leak or improper grounding," Campedelli says. "If they see anything, they call the equipment manufacturer and they will do their testing and the shielding manufacturer will get called in if it's not something correctable in imaging software."


Maintaining the Room

Currently, there are no requirements or guidelines by any agency to verify the integrity of the shielding on a regular basis, but that doesn't mean you shouldn't have it checked and tested regularly.

"You should do it once a year but if you test every other year you should have a good idea of a room," Vojak says. "You should clean the door at least once a month. Nothing other than the finger stock really wears out."

Typically, an RF test is $2,500 plus travel expenses. The tester usually provides a multi-page report and the calibration records of the equipment.

A low-tech way for people to test RF shielding is to bring a radio or cell phone into the room and shut the door. If there's no reception, it could indicate proper shielding. But in reality, while this technique could expose poor shielding, it's far from enough to ensure a that there is perfect shielding.

"That's a quick way for a client to check their RF shielding, but that's not going to guarantee there's nothing penetrating," says Larry Knight, CEO of Sunrise Medical Technology, Inc. "If you truly want to test the shielding, you'll need to use a signal injector and a spectrum analyzer. A spectrum analyzer paired with a good omni directional antennae will detect any RF signal that gets through the room. Usually, you can isolate that signal to within about a foot of the leak and then go about fixing the problem from there."

Mike Profeta says his company has initiated a quality maintenance program for its shielding customers.

"We initiated quality assurance and maintenance agreements with institutions to provide periodic testing and maintenance. The door is typically the thing that will fail first. It's a contact that is constantly being moved. But that's not all that happens. Other things happen over time, such as wood shrinking causing the seams in the compression type seals to fail, or contractors accidentally cutting a hole in the shield. Very few people address these issues until the images are bad," Profeta adds. "A good QA program includes regular shield testing and maintenance. Sometimes an MRI equipment problem can look like an RF shield problem so another real benefit to keeping shield performance and verification up to date is that it keeps the MRI service technicians working on equipment problems when they know the shield is performing properly."

Turner is amazed that some customers test the shields when the magnet is delivered but never test again until they decide to pull out the old magnet and put in a new one.

"A service or maintenance program needs to be put in place for these MR systems, maybe generated or driven by ACR, because the rooms can degrade over time and degrade in such a way that the hospitals may not recognize it and may get faulty images," Turner says. "The MRI people have specs for a reason. Something has to be done."


Upgrade Possibilities

Although upgrading your MRI system will probably not require any update of the shielding, it's still important to test the shield and fix any problems during the upgrading process. Since you are already going through the trouble of bringing in new equipment, it's usually a good time to evaluate other components of the shielded room and upgrade if needed.

"Sometimes a facility will decide to do an upgrade and then contact us to perform a qualification test, an RF test, to see what the integrity of the shielding is before we start any work," Campedelli says. "That gives us a baseline to see if the existing shielding can meet the new magnet's RF attenuation specifications."

Often, a shield will disintegrate over time in some areas. Those spots can be identified when the shield is opened up so when the old magnet is coming out before the new magnet comes in. In many cases, repairs are done at that time.

"Some of the things that are commonly done are the replacement of the door to the scan room, because a client will want one with a newer design and one that gives better shielding capabilities than the existing door," Campedelli says. "Other times, they will work in the area where the manufacturer's penetration filters come into the room because that's one of the weak spots in the shielding so they will upgrade or add electric filters."

Most shields have a warrantee of about five years, but some shields have been found to last 15 to 20 years or even longer.


Recycle Options

Let's say a clinic decides to get rid of its MRI for whatever reason and the shielding is no longer needed. Holder says that the material shouldn't just be thrown into a dumpster, because it has value.

"Some of it is sold for scrap," he says. "Copper in particular has a high resale value."

Some shielding can also be moved and continue serving the user in the new location, although you have to determine if the value of tearing it down, transporting and putting it back up with the possibility of damage is worth the risk.

"There are portions of the shield that can be reused. As a clinic or imaging center consolidates or moves, some components can be salvaged. It goes back to warranties and what you purchased, how recyclable the designs are," Krachon says. "The doors and windows, if maintained properly, can be used in a new setting. Copper panels can be relocated and may be put in place with new panels that would match the configuration of the new area. The challenge is in protecting them when moving from one site to the next."

Turner says that RF shield floors should never be used again because of wear and tear. "Walls and ceilings for the most part can be reused unless the customer purchases a wallpaper type of shield where they take material and staple it up to plywood or walls and ceilings," he says.


Choosing What's Best for You

"It is important to use a shielding company with experience who can provide a resume displaying past projects completed of a similar size. The shielding company should be familiar with the requirements of each MRI vendor as it pertains to the shielded enclosure and also be able to provide an enclosure that can be later modified to a different MRI system should there be a future upgrade," says Mike Newman of Universal Shielding Corp. "It is very important that the shielding company has its own staffed personnel perform the installation rather than companies that subcontract this work to independent installers."

General Contractors sometimes try to install shielded enclosures themselves or attempt to construct their own shields and many times they do not meet the MRI vendor's specification leaving the customer no recourse if the shield begins to fail.

Turner recommends when buying an MRI, you should perform an EMI study to detemine site suitability. Otherwise, if there are disruptive vibrations, you may incur unexpected costs.

"I have a customer unsure of what OEM to use but he wants to move forward with planning. So we can do EMI vibration tests and tell them whose spec they can meet so they know that in advance," Turner says. "The shielding vendor should work with the customer as best he can."

It is evident there is a lot going on behind the scenes and the walls of the rooms housing MRIs and it's vital to get a clear picture of your needs.

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DOTmed Registered MRI Shielding Sales & Service Companies
Names in boldface are Premium Listings.

Domestic
Miguel Machuca, Diagnostic Medical Equipment Solutions Corp., FL
Len Spooner, MagnaServ, Inc., FL
Dave Wayne, SE Medical Systems, GA
Benjamin Turner, ETS-Lindgren, IL
Michael Krachon, IMEDCO, IN
Lou Campedelli, NELCO, MA
Ralph Babcock, Imaging Affiliates, NC
Mark Holder, Global Partners In Shielding, Inc., NJ
Irwin Newman, Universal Shielding corp., NY
Conrad Smits, Philips Healthcare, NY
Irwin Newman, Universal Shielding Corp., NY
Bill Kearns, The Katonah Group, NY
William Mansfield, Professional Installations, OH
Gregory Vojak, Medesign, OH
Michael Profeta, Magnetic Resonance Technologies, PA
DOTmed Certified
Bart Wesselius, R-Box Mibile Testing, TX
Dustin Hess, National MRI Shielding, TX
Greg Grace, Shielding Dynamics, TX
James Spurlock, Radiology Facility Development, Inc., TX
Joseph Thompson, Assured Imaging Services, TX
Tommy Geske, Sunrise Medical Technology, Inc., TX
DOTmed Certified/DOTmed 100

International
David Holden, MarShield-Div. of Mars Metal Company, Canada
George Perez, Bioscan, Peru

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