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The very loud low frequencies I heard and felt were cool!

Discussion in 'General Electronics Chat' started by audioguru, May 17, 2017.

  1. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Today I had a Magnetic Resonance Imaging test on my neck to see if there is a pinched nerve or a pinched artery.
    I was asked many questions about if there is anything metal in my body and I said I think my Hernia repairs used stainless steel wires and my Heart Artery stents are metal. They asked if a piece of metal got in my eye and I said it was removed (the metal bit, not my eye) and an X-ray showed that it was gone.
    I was asked a few times if I am pregnant (I am an old guy!) and if I am certain that I am not pregnant.
    I was asked if I am claustrophobic and I said no.

    I was given ear plugs and an over the ears headphone was put on. It was clamped tightly to my ears. All I heard was my heartbeat until the machine was turned on.
    I was rolled into the very expensive machine that has its electromagnet super-conductor wire cooled with liquid helium.
    Then I heard loud low frequency pulses and felt vibrations for 20 minutes. Hundreds of diesel engine and motorcycle sounds. Fantastic, I wish I recorded the sounds. But I can never produce loud low frequencies like that.
    This test, a previous X-ray and a previous ultrasound cost me nothing since my government pays for most medical procedures.

    I got the cataracts in my eyes fixed, I got my heart attack blocked heart arteries fixed and now I will get my neck fixed.
     
  2. atferrari

    atferrari Well-Known Member

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    Congratulations. A Canadian cyborg in the making?
     
  3. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Is there any long waiting times to obtain certain medical treatments or procedures in Canada?
     
  4. dave

    Dave New Member

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  5. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    When I went for an MRI I was warned about the loudness, but untill you are actually in there..... Yes! They are loud even with the earplugs and headphones.... I couldnt believe how tight they make it... I'm not claustrophobic, but I did feel like a sardine..
     
  6. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    Me too, very loud.
     
  7. Musicmanager

    Musicmanager Active Member

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    I have been privileged to attend an MRI scan at 3 monthly intervals over the past couple of years, usually without issue at the main Trust hospital in our area, however, I had an appointment last year at the local 'clinic' who use a much older machine. I'm 6ft 2 and built like a 'brick khasi' and the mobility issues have helped the waistline develop at an alarming rate so I was very concerned when I saw the size of the hole they wanted me to fit into.

    I was nearly as embarrassed as the technician when they got me stuck in the machine, no not by my waistline but my shoulders ! I could move neither in nor out until an engineer arrived to remove the outer panel which he did whilst indulging in a great deal of sarcastic humour.

    I never got to experience the proper noise ! :D

    S
     
  8. Externet

    Externet Member

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    Wearing headphones in a magnetic resonance imager ? Do not get it... I can believe all-plastic ear muffs.
     
  9. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    Air pipe audio coupling tubes are often used, like the old fashioned stethoscope.
     
  10. AnalogKid

    AnalogKid Active Member

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    Eric is right. All plastic, over the ear cans connected to the audio source with hollow plastic tubing. Someone named 'audio guru' must have loved the sound quality.

    Over the decades I've had a few MRI's, plus I'm part of the ten-year knee study so I get annual shots of my knees. Every time I have one, the list of questions gets longer. MRi's taught me about eyelid wires (ouch!).

    My company built part of the image processing gorp for Picker (then Marconi, then Philips). When I was up there during the design phase (18 years ago), I went through the test and calibration line. Impressive, and loud, and yes, that field really can rip a tweaker out of your pocket.



    For an eddy current display, the object does not have to be a loop. My fav video (can't find it) uses an aluminum slab about the size of and encyclopedia volume. Notice that the angular velocity of the falling edge is almost perfectly constant, not accelerating due to gravity. It speeds up at the end because it is farther from the field source.



    ak
     
  11. JonSea

    JonSea Well-Known Member

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    I recently needed an MRI of my knee for a total knee replacement. The company that makes this implant builds a 3D model of your knee and customized tooling that snaps on to your bones, guiding the cuts the surgeon makes and aids him in getting the proper alignment.

    I had an MRI of my neck some years back. I'm a big guy, so arrangements were made to use a "large bore" MRI. No mention was made of that this time and since I just needed an MRI of my knee, I didn't think anything about it.

    I got positioned in the MRI, my knee in a cage which apparently provides a better image of a small area. The technician checked and made some adjustments and my knee was in the right location. Then he started to move the table further into the machine and looked confused. There was no way my torso could go into the machine with my arms attached to my body. Turns out, they also take MRIs of the ankle and hip to get the proper angles and to measure distances along your leg. Oops. I had to reschedule at a large bore machine.

    Surgery and rehab has gone well on the first knee (surgery was 8 weeks ago) and I decided to do the other one (3 weeks from now).

    Scheduled an appointment at the large bore MRI again and the same technician was there. The procedure is routine now. I get in the correct position after moving around a few times. Then there was a new twist. She put a sandbag on my "new" knee and wedged it in position against the side of the table. Turns out that even with the non-magnetic materials of the implant, it is somewhat attached by the field of the MRI. I believe the literature says the maximum pull is only about 4 pounds. If my knee hadn't been weighed down, it could have moved during the procedure and spoiled the image.
     
  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Before I went in, they said they would play music through headphones. They must have known about me because the headphones did not play awful-sounding music. I did not notice if the headphones had "sound tubes".
    The MRI machine must be used almost 24 hours each day because my appointment was in the evening.

    My medical problem is not serious so I waited 2 weeks for an eyes X-ray and 1 month for an ultrasound then another 2 weeks wait for the MRI appointment. If my problem was serious then the tests would be done the next day then surgery the day after that.

    In Canada some towns are far from civilization where few doctors go to work so the people there must wait a long time for medical treatments or travel far to a big city.
    Canada attracts many foreigners who are crippled or mal-nourished. They are the majority of patients at a medical clinic or hospital emergency department. Many foreigners clutter the medical department because they caught their first cold or have minor frost-bite. Newspapers complain that there is a lack of nursing homes for old bed-ridden people (most are foreigners) so they lay on stretchers for days in hospital hallways. I hope that never happens to me, I want to stay healthy and active until my life's end.
     
  13. KMoffett

    KMoffett Well-Known Member

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    Ever notice that medical shows on TV that show someone in an MRI (NMRI..."N" was dropped because it scared people) it's quiet as an X-ray. :)

    Ken
     
  14. Musicmanager

    Musicmanager Active Member

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    Jonsea, you're a lucky guy !

    2 years ago I was scheduled for a hip replacement - even got as far as the pre-med the day before. Unfortunately, the surgeon changed his mind because the pre-med detected Phlebitus and he says it will stop the healing process.. .. .. .. .. .

    .. .. .. .. .. . so I hobble around like that guy out of Gunsmoke .. .. .. .. .. Mister Dilllon ? .. Mister Dillon ??

    bar of chocolate, if you can remember his name ??

    S
     
  15. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    • Funny Funny x 1
  16. KMoffett

    KMoffett Well-Known Member

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  17. Musicmanager

    Musicmanager Active Member

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    Nope !
     
  18. Musicmanager

    Musicmanager Active Member

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    sorry, the 'Nope' was for Festus ... .. .. ..

    Chester is the RIGHT answer .. .. .. .. .. . Well Done, Ken !

    Now the thing is, if you're old enough to remember Chester, you shouldn't be eating chocolate at your age !! :D

    S
     
    • Like Like x 1
  19. atferrari

    atferrari Well-Known Member

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    Around 30 years ago I visited the plant of ALUAR (Puerto Madryn - Chubut, in the Patagonia), producing aluminum ingots. At that time they had 220 electrolytic cells installed requiring lot of current. To demonstrate that, our guide dropped a coin that landed on the ground, almost vertical, following the direction of the field there. Coins at different places adopted a different orientation.

    Power comes from the Futaleufú power plant , some 450 Km away, located at the lake Amutui Quimei (mapuche name) . They later added gas combined generation and IIRC, installed cells nowadays amount to 800.

    In few days I expect to be at Madryn discharging parts for 12 windmill units. Nice place with friendly whales in the Gulf.
     
    Last edited: May 19, 2017
  20. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Getting older is so much fun and we learn new and exciting things about cool stuff.

    I have had a few MRIs done and assured them I was metal free. Well one tiny stainless screw in my neck. So a week later we go out to dinner and they had to manually enter my credit card number. A few days later the ATM would not give me cash, it couldn't read my card. Then came the sinking feeling in my gut. I was metal free and had my wallet in my pocket as went through the MRI. Me, who should have known better took all my magnetic strips on a ride through the MRI and yes, those things are loud. :)

    Ron
     

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