Re: secondary x-rays from ultra-sound:proved to exist

[Brian_Gaulke@hc-sc.gc.ca]

It is my understanding that ultrasound at high enough intensities will produce
cavitation.  The collapse of the bubbles produced can generate temperatures of
order 10,000 degrees - high enough to generate plasmas.  The resulting plasmas
can emit x-rays both through brehmstrahlung and as the temperature drops and
electrons are re-captured.

Diagnostic ultrasound, however, is always carried out at intensities well below
the cavitation threshhold.

Just my personal thoughts.

Brian R. Gaulke, CHP
Brian_Gaulke@hc-sc.gc.ca





Jim Vandergrift <jfvande@yahoo.com> on 99/05/14 06:03:07 AM

Please respond to radsafe@romulus.ehs.uiuc.edu

To:   Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
cc:    (bcc: Brian Gaulke)

Subject:  Re: secondary x-rays from ultra-sound:proved to exist




This seems energetically impossible to me. The only "x-rays" possible
are characteristic x-rays.  In order for them to be classified as
"ionizing" radiation they must be 13.6 eV or greater.  The only
electrons available to be effected by mechanical collisions as with
ultrasound or thermal processes are the "valence" or outer electrons.
It seems unlikely that these electrons (in biological systems) will
have binding energies of 13.6 eV.  To associate ultrasound and x-rays
simply because of their associated "wave" properties is to demonstrate
a fundamental ignorance of both processes.

--- Rachid Zitouni <azittouni@yahoo.com> wrote:
>
>
> --- LAM HOI CHING <lamhc@hkusua.hku.hk> wrote:
>
> > Ultansonic wave is only a kind of mechanical
> > effect,it is a kind of
> > macroscopic phenomenon in the material, it affects
> > only the mechanical
> > vibration of atom, but  not to the atomic
> structure
> > change like the atomic
> > orbital,whereas x-rays are due to internal
> > transition of atom or molecules,
> > in fact from electrons of the atom, these two
> > effects are not in the same
> > category.
> >  But you can discuss ionizing damage from x-ray
> > (doses)
> > or you can still discuss the harmful effect of
> > ultrasound. The two types of
> > interactions (by ultra-sound and x-ray) are
> totally
> > different.
> >
> >
>
> Few years ago, I would have agreed with you. Yes,
> ultrasound acts on
> the bulk of the matter, at the macroscopic level and
> X-rays at the
> electronic level.
> Ultrasonic waves are not supposed to ionize matter.
>
> BUT:
> Very low Enegy X-rays have been detected following
> diagnostic
> ultrasound. I lost track of the paper which was
> published on this
> subject.This phenomenon has been proved to exist. I
> haven't done the
> experiment myself, but I suppose the excitation of
> matter by ultrasound
> at the molecular level may, under certain
> circumstances (which are to
> be determined), give rise to very low energy X-ray
>
> By the way, I haven't referred to any biological
> effect related to
> these low-energy X-rays. In fact, the dose in this
> case is meaningless.
>
> Thanks for the reply and keep digging if the subject
> is of interest to
> you.
>
> Abderrachid ZITOUNI, health Physicist
>
> azittouni@yahoo.com
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