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OT. MRI & the magnetic pull from it.

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  • OT. MRI & the magnetic pull from it.

    Guys showing just how much pull an MRI machine has on ferrous stuff. If there ever was any question of why you don't get into one of these things accompanied by anything ferrous, especially internally, this video answers it.

    http://www.liveleak.com/view?i=78d_1310769320

    Another site that shows some of the stuff that has gotten sucked into an MRI...

    http://www.simplyphysics.com/flying_objects.html
    Last edited by Arcane; 07-17-2011, 10:10 PM.
    Location: Saskatoon, Saskatchewan, Canada

  • #2
    They keep making them stronger too. There is a limit though. In a strong enough magnetic field blood acts as a ferro fluid. Pump up the field high enough and it turns to gel. Not a good thing.
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    • #3
      I have had several MRI's and they always ask if I work with metal and when I answer yes they x-ray my eyes. They told me you can have a small metal piece in your eye and not know. I guess they found out the hard way and I bet it was not pretty. If don't ask I would tell them!!

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      • #4
        Bill,
        Then I had my MRI two weeks ago they asked if I had ever had anything removed from my eye by a doctor. I said maybe. I remember once going to emerg on an eye issue.
        They did not offer an Xray.
        I got the MRI on Knee and I did not have any issues. :-)
        Dave

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        • #5
          Sorry for the blatant thread jack Arcane, but this video shows up next to yours, showing Buzz Aldrin punching a 20-something in the face for accusing him of lying about walking on the moon -- LOL!

          http://www.liveleak.com/view?i=39cc406620
          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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          • #6
            A similar though not quite as severe danger can come from commercially available HUGE neodymium magnets. These may be as large as lathe chucks, and if two of them fly toward each other from a distance away, as I understand, you may have to deal with neodymium-iron-boron shrapnel.

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            • #7
              thats why I am not alowed to have mri......too many bits of metal


              nice one Buzz

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              • #8
                those machines cost a million upwards ..why are they abusing it in that video.

                they got money to burn or something

                all the best.markj

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                • #9
                  Nervious system

                  Originally posted by Evan
                  They keep making them stronger too. There is a limit though. In a strong enough magnetic field blood acts as a ferro fluid. Pump up the field high enough and it turns to gel. Not a good thing.
                  Nervous system limits are hit long before magnetohydrodynamic limits. You start seeing and feeling things. Very disturbing to the patient long before its fatal. They pretty much operate at this limit now.

                  The other limiter to performance is noise, huge forces on flexible objects inevitably make sounds that terrify the patient, kind of like submarines popping and creaking when changing depth, structurally safe but scary, and once you get over 100 dB or so you really need to earplug the patient. Not just scary but you can actually permanently damage hearing.

                  The page below is titled "Part 6 MRI Safety for Healthcare Personnel"

                  http://www.ceessentials.net/article7.html

                  They used to build most of the worlds MRI machines a mile or two north of my house... I knew people who worked there, although not directly on the machines. Pretty cool machine tool work. Now I'm sure its all China / India from top to bottom like everything else... our loss.

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                  • #10
                    Interesting. I had an MRI last month and was asked about any possible metal hanging around, and told them yes. They x-rayed my eyes (all clear) and I informed them about the couple of chunks of bearing steel I carry around in my left wrist. They asked how long they have been there, and I told them it's been several years.
                    To which they replied "Oh.... it's ok then."

                    From what they told me, it is more of a concern about the metal heating up and causing internal burns, not unlike a microwave. Apparently if you build up enough scar tissue around the metal over time it's no longer a concern to them.

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                    • #11
                      The scar tissue is very strong and will prevent small pieces from moving. Pieces in the eye are often sitting in the eyeball in the Aqueous humour or the Vitreous humour and are free to move. Any heat buildup in small pieces is easily conducted away.
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                      • #12
                        I've wondered about this. My wife has had 3 MRIs to date. The most recent about a month ago. She has stainless steel pins and a plate holding her wrist together and a surgical stainless barbell in her tongue. This time they didn't have her remove the tongue piercing and she didn't notice anything amiss.

                        I know stainless isn't very magnetic, but I would have thought it would be affected by the field.

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                        • #13
                          many moon ago i went to a MRI factory, in the workshop there was a coil assembly undergoing testing, the guy taking us round did his party trick with a ring spanner on a rope, the rope was quite thick, he threw the spanner at the coil and it shot towards the coil, pulling the rope tight and horizontal, the spanner was several feet from the coil!., i wouldent fancy getting mri'd i've got titanium heart stents, dont think they mix too well, but truthfully i dont know, perhaps i should get one of those alert bracelets or somthing?[ i didnt have the metalwork when visiting Siemens!]
                          mark

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                          • #14
                            If you follow Arcabne's second link, and review the list of photos, one of the photos links to this page. The first para is a comment on the photo, but I was interested in the story that followed.

                            http://www.simplyphysics.com/flying_...lenetorch.html

                            I wonder how they decided whose fault it was.
                            Richard - SW London, UK, EU.

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                            • #15
                              Originally posted by aboard_epsilon
                              those machines cost a million upwards ..why are they abusing it in that video.

                              they got money to burn or something

                              all the best.markj
                              Old machines have no real value. Its not like you can send them to some third world country or something. They need liquid helium to keep the superconducting magnets chilled. Just looked it up, average of 1700 liters of liquid helium in one. Thats a pretty big chunk of change and it keeps evaporating.

                              Heres one that ruptured when it was being moved. Though the magnet looks more like an NMR magnet than a MRI.

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