Magnetic Effects

athar at athar at
Sat Mar 1 23:26:46 EST 1997

Douglas Rand wrote:
> Adam Reed wrote:
> >...
> > with the magnetic field of the MRI.  When the magnetic field is turned off,
> > the water molecules will return to the relaxed state, resulting in the
> > production of gamma radiation.  The body is the source of the gamma
> > radiation.
> Please read up on this before you scare someone.  The atoms don't reach
> an excited state and as far as I know there isn't a sufficient energy
> level in an electron's orbital state to cause a gamma ray (or even a
> soft X-ray) to be emitted.
> What *is* emitted by the aligned electrons (I believe it's just the
> hydrogen atoms,  but my chem. courses are about 20 years ago) are radio
> frequency radiation.  That's picked up by very sensitive detectors and
> turned back into a 3d map.  There's no ionizing radiation involved at
> all.
> For the curious: As I remember this,  gamma radiation is defined as
> radiation from nuclear events and things like particle destruction.
> X-rays are normally generated by momentum changes in electrons (usually
> braking radiation as the electrons interact inelastically with an
> atom).  The electrons involved in X-rays have been accelerated into a
> target of a dense material,  titanium used to be the material of
> choice.  I don't know about modern X-ray tubes.  In any case Nuclear
> Magnetic Resonance (the real name for MRI,  but unused since "Nuclear"
> scares everyone) doesn't involve accelerated electrons,  nuclear decay
> or matter-antimatter anihilation,  so you're safe.
> Doug
> --
> Doug Rand                               drand at
> Silicon Graphics/Silicon Desktop
> Disclaimer: These are my views,  SGI's views are in 3D

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