Should I be looking for safer ready-storage techniques over the use of these magnets or are they simply not strong enough to cause the type of discharge mentioned in this article?

So far I’ve had no problems at all, but if there’s even a remote possibility of an accidental discharge caused by the magnets themselves, I’ll be changing things ASAP.

Those “no metal objects” rules are to protect the machines more than they are meant to protect the patients. Funny story, though; I’m glad no one was hurt.

A friend of mine, when his GE Signa scanner (same model, as close as I can tell from the article) was being installed, tied a wrench to a string and attached it to the doorknob to the room. When the door swung in, it got close enough to pull the wrench toward the magnet, so it quickly ( < 1 sec ) was pointing straight at the magnet. A good visual clue. Closing the door got it _just_ far enough away to drop back down. He did that to remind the contractors who were doing finishing work that “we meant it, guys.”

However, people do dumb things. I’ve had folks tell of patients, where the elderly gentleman was on the bed being pushed into the scanner, when his wife asked, “That sign about no metal and no pacemakers… it doesn’t apply to _him_ does it?”

I’m not sure where I stand on this. I mean, the cop disobeyed big signs, on a misunderstood verbal OK. Yeah, and if a cop is at the corner directing traffic, he is the sign, not the traffic light. So in his mind a verbal OK overrides the sign. And granted, carring a 1911 locked&cocked is not unsafe; there’s not one but two safeties, then you still have to pull the trigger.

On the other hand, carrying with one in the pipe in a hospital environment seems pretty damned dumb. But I’m not sure how much of that is common sense and how much is just the respect for big magnets that can only come from experience.

annoyingly, the report doesn’t seem to mention if the primer was dimpled by the firing pin or not. that’s frustrating, since it does mention the casing was recovered.

I’ll have to read the report when I have more time. If the gun fired on impact with the machine then the eddy current hypothesis should be thrown out.

At the field intensities of an MRI, just about anything with a substantial iron content can be considered magnetic. There’s some magnetism even in the non-mag stainless alloys, but you can’t really notice it at normal field intensities. At the 10k to 20k Gauss of an MRI machine? I’m not taking any bets on stainless not exhibiting magnetic behavior. That’s a whole bunch of field.

Non-ferrous metals can get eddy currents; I used to work with them quite a bit. I’ve seen copper go cherry and aluminum slag down in magnetic environments within seconds.

For more MRI fun: http://www.simplyphysics.com/flying_objects.html and http://www.simplyphysics.com/burnsinthemagnet.html

PS – it seems this is an event from 2001 or earlier

Dr Strangelove – I not so sure an aluminum can would be affected by a magnetic field? The same doubts apply to stainless steel. The officer should of been carrying a stainless Colt…

I’m wondering if it was something other than the firing pin striking the primer that fired the gun. The changing magnetic field would have created eddy currents in the metal. Those eddy currents would have heated all the metals. As soon as the primer reached high enough temperature it would have gone bang.

The question to ask is why all the cartridges didn’t go bang. If they shut down the MRI shortly after the first one went off then that could explain it. Another explanation could be that the metal of the chamber concentrated the magnetic fields. The rounds in the magazine didn’t have similar concentration.

Thanks to eddy currents, I wonder if an aluminum can, if placed in the field, could be yanked out fast enough to either rip it apart or melt it…

If the primer’s stem was made of steel, could it have been shifted enough to light off the priming compund?

If that’s the case, *no* safety would have helped.

a) Take it on in there!
b) Leave it with the MRI Tech.
c) Leave it in the car

…”I’m the only one in here qualified enuff”…

This seems like one of those events, although you could easily say the cop should have known better than to bring his weapon into the MR area and that by doing so, he was negligent.