Re: MRI Machines

Jim Thompson wrote:
On Tue, 24 Jun 2008 11:34:07 -0700, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Tue, 24 Jun 2008 13:28:46 -0400, RFI-EMI-GUY
<Rhyolite@xxxxxxxxxxxx> wrote:

Well I spent a half hour of my life under the magnet of an "open" MRI machine yesterday. Still a bit claustrophobic. While I sort of understand the theory of the MRI, what I don't understand is what creates all the noise and racket. Any experts out there that can tell me whats going on?
Pulsed gradient coils. These are "small" 3-axis coils that sweep a
gradient field across your innards, modulating the nuclear resonant
frequencies of your molecules to produce the spatial resolution. These
are generally water-cooled, with ballpark 20 KW constant-current
drivers per axis, playing all sorts of weird waveforms.

They scanned my head last year, with the gradient coils around my head
like some horror mask: noisy and boring.

John

A few years ago they scanned my sinuses.

I must admit a claustrophobic feeling also :-(

...Jim Thompson

I told the tech to give me a time check every so often so I wouldn't lose my mind, then I worked out a design problem in my head for 30 minutes as a distraction. I can put up with a lot of stuff but being inside or under that thing creeps me out. I keep having visions of oxygen cylinders getting sucked through the drywall and crushing me or the magnet quenching and getting burned in a puff of steam.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P
.

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