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MRI and high magnetism danger

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Chris Vincze

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Hi there,

we're due to film a Magnetic Resonance Imager (MRI) scanner soon. Does anyone know what sort of magnetic field this might produce, and if it's possible to shoot it on the RED One? Will the magnetic field interfere with the electronics or media? How close/far away would you have to be to shoot?

Any info the RED team, or anyone with experience of this kind of equipment, could give on this topic would be massively helpful.

Thanks a lot

Chris
 
I'd personally not take any camera or anything made of metal in the same room as one. Very dangerous indeed. Whenever I've had an MRI scan, I've had to remove all metal from my person before entering the room. Because they use liquid helium to super-cool their magnet, you can't exactly "switch them off" either.

Graeme
 
There have been great discussions on CML about filming MRI's in the past with all sorts of cameras.

The couple times I've done it the MRI unit was always in "demo" mode so there was no active magnetic field.
 
There was a fun story in the PPA magazine (pro photog. of america) a year or two ago, about a still photo shoot on an MRI. The photographer was told the machine was off, so he approached the bore with his rather pricey camera, and BANG! the field grabbed it right out of his hands, smashing to pieces against the interior wall. Fortunately the only casualty was his camera, and not the MRI itself (several million $). Turns out the field was ALWAYS on, at least with this particular model (and I think many are like that). So yes, the warning signs about "no metal" apply to photographers too, regardless if the imaging system is on or off.

"The magnetic field and the associated risk of missile-effect accidents remains a permanent hazard — as superconductive MRI magnets retain their magnetic field, even in the event of a power outage." (from http://en.wikipedia.org/wiki/MRI#Safety )
 
I have shot them at least a dozen times on Varicam, and never had any problems. Obviously not in the same room when it was on, shot thru the glass where the tecs where, CUs etc while machine is off. The techs usaully tell you whats safe and whats not.

Nick
 
Thanks for all the responses. It sounds like there are a couple of types - ones which are always on and thus sounds like a no-no for any kind of camera; and ones that have a demo or off mode which are ok, at least for a varicam. Does that sound right, or have I misunderstood. I guess I at least need to speak to the scanner techs, but from Graeme's post it sounds like a bad idea....
 
MRI experience..

MRI experience..

I've shot these many, many times. They produce an incredibly strong magnetic field, and the hospital or imaging facility will likely have strict guidelines for safety. You will not be able to put any gear inside the room where the imager is. We've always had to shoot through the window the operator uses, which is often lined with a perforated screen. Occasionally, we've been allowed to put one light just inside the door. The field is strong enough to distory the scanning of CRT imaging tubes and monitors, but I've noticed no effects on CCD cameras. It's certainly strong enough to erase magnetic media, so I dont' know what effect it will ahve on hard drives, which are magnetic.

Good Luck!
 
jbeale said:
There was a fun story in the PPA magazine (pro photog. of america) a year or two ago, about a still photo shoot on an MRI. The photographer was told the machine was off, so he approached the bore with his rather pricey camera, and BANG! the field grabbed it right out of his hands, smashing to pieces against the interior wall. Fortunately the only casualty was his camera, and not the MRI itself (several million $). Turns out the field was ALWAYS on, at least with this particular model (and I think many are like that). So yes, the warning signs about "no metal" apply to photographers too, regardless if the imaging system is on or off.
Click to expand...

See http://en.wikipedia.org/wiki/MRI#Safety and think twice as the projectiled items will end up in the center of the magnetic field - and thats where someones head is...
 
If you go behind the screen. Consider bouncing lights onto foam or walls to get the light where you want. (the screen is usually open sided) I have absolutely 0 knowledge in these shooting conditions however, so double check all that info.
 
Danger!

Danger!

supernovafilms said:
If you go behind the screen.
Click to expand...

DANGER!

I read in the paper some time ago I think that someone left a gas bottle in the room that was not locked down properly or something, anyway there was a boy in the machine to be scanned and when the MRI was switched on the gas bottle took off and flew into the MRI and killed him!

It could be a big mess if someone turned the machine on when you were in the room shooting, there should be double circuit breakers on the power to the machine, the first one turns on bright red lights, the second one (in series) turns on the power to the machine, both turn off the power, that way if the lights are on you know that power is possable even if it is off with the second circuit breaker box.

A plastic mirror might be able to be used to get a shot if you use a long lens into it? The plastic mirror or black plexi might be held up with a cardboard stand and masking tape. Test without someone in the machine!
 
www.DANCAD3D.com said:
DANGER!

I read in the paper some time ago I think that someone left a gas bottle in the room that was not locked down properly or something, anyway there was a boy in the machine to be scanned and when the MRI was switched on the gas bottle took off and flew into the MRI and killed him!...
Click to expand...

See post #8 from Robin Balas above - it has link to Wikipedia which links to actual warning video to all MRI facilities where your story is confirmed.

Ferromagnetic metals seem the worse, but any metal (unless you're certain it has no ferromagnetic content) is high risk, and some MRIs have a permanent magnetic field regardless of whether the machine is switched on or not. So safety is going to dictate that there is zero metal brought into the machine room I think. Too easy for some little bit of kit to be overlooked and become a missile.
 
I have designed the magnetic circuit of an MRI magnet, so feel like knowing something of the subject. First of all, there are two kinds of magnets. Those exploiting permanent magnets and those having superconducting magnets. In general, the very idea is that the field inside the magnet is very high in the range of 0.1 to 2 Tesla or even higher. But, the design goal is also that outside the magnetic field should be small. Still, the field outside is stronger than in ordinary environments.

The superconducting magnets have a stronger field than permanent magnet MRls. In addition, there are two type of MRls; open and closed ones. The closed ones are like tubes. The open ones generate a bigger field outside.

The static magnetic field creates a force which acts on ferromagnetic bodies, such as iron, nickel and cobalt. In addition, there will be a force on all wires carrying a current. The forces on so called paramagnetic, such as aluminum, and diamagnetic materials is very small. In fact, the aluminum body creates a good shield against alterning magnetic fields. Furthermore, the aluminum body will create a repelling force if one tries to quickly move the camera towards the magnet. (There will be so called eddy currents within the body which try to act against the effect of changing magnetic field when the camera is taken quickly towards an MRI magnet. This is known as the Lenz law in elementary physics.)

MRI magnets include also RF coils and what comes into mind is that the camera may (probably will) affect the imaging and the other way around the RF coils may get the camera to malfunction.

The effect of the static magnetic field and the RF coils decrease approximately to the inverse of the square of the distance. So, staying far enough of the magnet is a good practice implying neither the imaging or the camera is damaged.
 
Hi Chris,

we filmed a lot of MRI systems over the years. Important to be very aware of the invisible magnetism. Every system has the so called GAUSS lines. The operator knows them. NEVER go within these lines, it will result in dangerous situations on the one hand, and in possibly distorted images on the other hand.

Wise is to stay in the doorway or in the most far away corner of the room.

EXTRA WARNING: be very carefull with light you place. It IS possible, but when placing and removing it, be very aware of the fact that within no time it is pulled into or to the magnet.

This all having said, it is possible, but, never alone, with professional techs surrounded, it can be done.

Remark, we never did this with the RED so far, so no specific info on that.

enjoy!
Leon
 
Thanks for the input. I have found out that the one they were thinking of using is always on & so I've advised against shooting there from all the responses here. Apparently it's an extra thing they thought would be nice, but not essential to the script. I'm sure if they decide they really want it they can use a prop scanner. Useful to know though!
 
If it's of interest, here is the story about the fatal MRI oxygen-cylinder-missile accident (Valhalla, N.Y, 2001). The nurse who brought the tank into the room thought it was aluminum, but in fact it was ferromagnetic (steel I presume) and the 6 year old boy in the MRI was killed by the impact.

http://www.webmd.com/news/20010801/fatal-mri-accident-is-first-of-its-kind

As the article says, accidents are very rare. BUT, MRI machines (particularly the superconducting-coil type, where the field is always on even during a power failure) require constant vigilance... nowhere else in life do you encounter that strength and size of magnetic field, so most people have no experience with what it can do if any ferrous metal gets in range.

EDIT: If you look at the final example at Lowdown's link here: http://www.simplyphysics.com/flying_objects.html
you can see a video of exactly what Paulee is talking about below- an office chair hanging in midair as it is pulled off the MRI with a rope!
 
One more war story- my mother-in-law worked as an X-ray tech at the local hospital. The MRI was undergoing maintenance by the manufacturer. Apparently, the worker was a bit too relaxed in his safety procedure and mistakenly brought a metal stool into the room to reach something up high. The MRI grabbed it from him and launched it across the room to the machine. Because it took so long to calibrate the machine after a shut-down, they tried to pull it off instead of shutting it down. No amount of people could pry it loose. Finally, the fire dept. came and used a winch from their truck to pull it free and apparently it hung, horizontally, most of the way though the room as if gravity was switched to the side. She also said it's not uncommon to see dents in the housing of the MRI from impacts.
 
jbeale said:
... nowhere else in life do you encounter that strength and size of magnetic field
Click to expand...

If one wants to be precise, one does encounter rather strong magnetic fields by handling permanent magnets. Especially, the neodymium-iron-boron magnets are "strong" and if one takes such a magnet next to the hard drive the field is probably locally much stronger than that generated by a MRI magnet couple meters away from it.

Magnetic field is a certain form of energy -the magnetic field (which is the pair {magnetic flux density, magnetic field intensity}) is an auxilliary notion and one may well argue it is only part of the model- and as jbeale suggests the uniqueness of superconducting MRI magnets is the very high amount of energy stored in the magnetic field. This energy is the work done by the generator when creating the field.

Now, when a ferromagnetic object is taken close to a MRI magnet, the energy stored in the field changes and a force is discovered as the nature always tends towards the energy minimum. Compare, explosives (or the Red Lion battery) include a risk because a high amount of energy is stored in chemical form. The risk is to unintentionally alter the energy. The best way to aroid hazards is to avoid going too close.

The people operating the MRIs should know all the safety regulations. However, they do not necessarily know how to react on a camera because that's not included in the safety manual. Perhaps a good idea is to check the MRI vendor and call their tech dept for further instructions.
 
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