Re: MRI Machines

On Tue, 24 Jun 2008 11:57:30 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

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 :-(


That's probably because you guys don't have a house with a narrow crawl
space.

No crawl space, but I can stand up straight in my attic... now
partially floored for storage.

At least you can be sure that there won't be critters such as
rattle snakes waiting inside that MRI tube.

Mostly scorpions around here ;-)

...Jim Thompson
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