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health advisory Hospital Health advisory 2007-11-16 5:21:00

The fixed metal objects are just that--fixed. Plus, if they are either nonferrous (no iron in them) or are made of stainless steel, they will be nonmagnetic. Suspended ceiling grids are most often made of aluminum, so they are safe.

Any loose metal could and often does cause a problem. When MRIs were new, a medical tech I new carried into an MRI room several objects including a metal fan. The fan was jerked out of his hands and flew into the MRI machine with a loud clang accompanied soon after by loud cursing from those who knew that the machine would have to be shut down and readjusted.

A WW2 vet that I know cannot have an MRI because he carries grenade fragments. The magnetic field will pull them around in his body.

But metal objects that are fixed and will not fly around the room or are made of a nonmagnetic material are safe enough.

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Maybe these pictures will demonstrate how strong MRI magnets can be

http://uk.search.yahoo.com/search/images...

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All of the metal in these MRI suites is non-ferrous (or at least it should be)

The magnetic field is highly attenuated by the system so that their is a very small fringe field outside the magnet, proper. Normally, a magnetic field would behave as 1/r^2. This means as you move close to the magnet. The field will get 4x as strong going from 2 meters to 1 meter, for example.

MRI system though behave as 1/r^7. This is DRASTICALLY stronger meaning that if you have something ferrous in your hands, you likely won't be able to hang on to it once you begin to feel the magnetic field.

I hate to say it but I'm an MRI researcher and I've lost innumerable pens into the system which took a great of work to get out. Why? I didn't think they were strongly magnetic and all of the sudden, they are out of my pocket.

All of the things you saw in the room were likely MRI safe, i.e. non-ferrous. Magnetic and metal are used interchangeably by those without a good background in magnetics however they aren't synomyous. There are fewer magnetic materials than there are total materials in the world.

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