A permanent magnet MRI machine has many advantages, including low maintenance costs, no reliance on helium, and minimal electricity requirements... but it also has a powerful magnetic field that cannot be “turned off”.
To learn more about the power of an MRI magnet, click here.
When installed in a properly shielded MRI suite, an MRI poses no risk to people or equipment outside the scan room. However, removing and transporting a permanent MRI magnet (such as a Hitachi Airis II or Airis Elite, Siemens Magnetom Open C, GE Ovation, or Philips Panorama) requires special provisions to protect people and equipment.
If you are involved in removing, relocating, or installing a permanent magnet MRI, be sure you are working with teams who know how to properly and safely handle them!
What are the dangers in handling a permanent magnet MRI?
Danger to Yourself – The picture on the right shows a permanent magnet that was not properly shielded when an unexperienced team began to move it (remember, lots of folks handle the system downstream of your site). I can promise you that if your fingers were caught between these tools and the magnet, your fingers would lose (literally)!
Danger to Computer Equipment – The powerful force of these magnets can erase data and critical code stored in computers when in close proximity to the magnet. An experienced MRI engineer will ensure that the magnet is isolated or moved at a safe distance from other sensitive computer equipment during removal and when loaded into a truck or shipping container.
Danger to Your Wallet – Permanent magnets have been known to wipe out the data on bank cards, hotel keys, or anything else that utilizes a magnetic strip on the back. Leave your wallet, keys, and cell phone in a safe place.
Danger to the Unsuspecting Public – It would be unfortunate if a permanent magnet were to interfere with an innocent bystander’s pacemaker. The magnetic field travels with the magnet. Even when it’s off your property, in a truck and heading down the road, such safety problems are possible if the magnet is not protected properly.
How do I protect myself and others from the magnet during removal & transport?
Traditionally a custom made steel lined wood crate or transport box is built to reduce or eliminate the possibility of the magnetic pull affecting anything in close proximity. These specialized shipping crates can cost around $10,000.
However, one of our trusted engineering partners, Bill Mansfield of Professional Installations in Cleveland, Ohio told me of a creative way to shield a permanent magnet during transport without having to use a heavy and expensive shielded wood crate.
A Creative Solution...
Any permanent magnet MRI more than .2T in strength could be wrapped in silicon steel sheeting.
These are Type M36 silicon steel sheets that are typically 10’-12’ long by 4’-5’ wide and 20-26 gauge thick. Each sheet weighs about 50 lbs. They are simply placed around the face of the magnet (with covers off and first wrapped in a protective hardboard material) one at a time, one sheet placed directly over the previous sheet, until the magnetic field is dissipated enough that when the outer-most sheet will not “stick” the magnetic field has been adequately dissipated from its potentially harmful effects on people and equipment.
Check out this video that shows silicon steel sheets being installed.
We’ve had great success in safely moving permanent magnets using silicon steel sheeting. Since safety should be no secret, I would be remiss to keep my most trusted source for this material to myself. I receive a high level of service and a fast delivery time at a fraction of the cost of a custom shielded magnet box when I order silicon steel from John Carlson at ETS Lindgren. Call him for help with other RF shielding products as well.
Does your MRI engineer know how to safely move a permanent magnet MRI system? If not, call the Block Imaging project management team. We’d be happy to help!
Meet the author - Chad Husted