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[IP] Re: MRIs and pumps

    Dawn has bypassed the MRI-pump problem but I would like to try to clear
some things up in my mind by exposing them to this list--and wait for
anything to hit the....
    Yes, rays is incorrect. I think that electromagnetic field is what
should have used ( maybe a little bit awkward). Now, some things from a
physics text.
    Some metals are not effected and some are only slightly effected by
these fields. The evidence for this are the metals that are commonly use to
repair teeth--dental work. These restorations usually do not preclude MRI
    There is a group of metals that act (very weakly) in a way that is
opposite to the action of the ferro metals that we normally think of along
with magnets. Copper and lead belong to this opposite acting class.
    The lead shield that the MM engineer referred to may not be an error on
his part. A lead or copper shield should be very slightly repulsed. But the
problem concerns the operating technician ,not the patient in the 'tube'.
The operator is not going to be exposed to 10,000 or 5000 gauss ( Dawn's
    During two MRI sessions my pump was placed on a table that was very
close to the operator's station. I was ignorant and trusted their direction.
Nothing seemed to go wrong with my pump.
    MM has given their limiting number to Dawn-- 1000 gauss. To me the next
step would be to get the exposure number at the operators station from the
MRI's manufacturer or the installer. That figure had to be determined before
it was approved as a medical device. In addition, I vaguely recall these
imaging machines are periodically checked for safety ( in this state) and
these people would check the operators exposure.  Shielding may not be
     The field orientation question is also for the manufacturer. From my
amateur's position, I don't see how that would make any difference to the
pump.        Peter

>  Dawn, I would find someone at the pump company who knows exactly what the
> pump-radiation problem involves and can evaluate your technical situation.
> major question is 'can anything be done to protect an operating pump from
> these rays? Electrical circuits can be designed or shielded to protect
> from this environment. Maybe you could wear a light-weight shield around
> pump.

But, wasn't the original *problem* about Dawn working with MRIs - not
rays/radiation? The MRI (Magnetic Imaging Resonance(?) ) as Jan C has said,
is VERY strong magnets that will rip apart a pump. These are not *rays*.
People with steel plates in their heads or elsewhere in their bodies cannot
have MRIs. A boy was killed in one when someone forgot to remove a metal
wastebasket from a room and WHAM it went right in. A lightweight shield
would do no good as it would have to be metal and be ripped off.

IMHO the pump must be removed each time when dealing with a patient in MRI.

> Date: Tue, 8 Jul 2003 12:51:25 -0700 (PDT)
> From: Dawn Vesneske <email @ redacted>
> Subject: [IP] Re: insulin-pumpers-digest V7 #381
> In reference to the pump and MRI
>  The magnet utilizes a magnetic field of .7 Tesla which is stronger than the
> earths magnetice field. I wish i could tear the pump apart and look at the
> mechanism
> I already contacted minimed 4 months ago
 > 1st the engineer said wear a lead shield....Thats when I lost trust ( I would
> be sucked in the magnet) and he's an engineer?
>  I told him he's thinking of a Cat Scanner which is also a
> contraindication...which I dont understand why as it uses Xrays .
> They did say I could go in if the field  at less than 1000G ..I think
> heres the physics if anyone is interested  a refrigerator is 10millitesla
>   MRI 1.5 Teslas = 10,000 gauss
>   Low field MRI .7T = 5,000G my guess
>   earths magnetic field 30 microtesl =.3G
 > It may be only affected if its a vertical vs a horizontal field? Only testing
> on this would answer.....I dont think minimed would be interested for that
> research as Im probabaly the only MRI tech with a pump?
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