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Re: LNT and resources [Was: Scientific responsibility]
Gary,
I agree about the cost differences in a PET facility.
My comment went to the idea that construction costs
for items like shielding or ventilation are often
factored into the budget and are "recovered" over the
life of the facility.
--- Gary Isenhower <garyi@trinityphysics.com> wrote:
> You are quite right that the difference in cost
> between 1/32" and 1/16" is not a big deal.
> Roughly 70$ per panel vs 110$ per panel. However,
> you will find that this is not a
> "linear" function if you go to thicknesses greater
> than 1/8". There, the increase in cost
> is VERY significant, particularly for a ceiling
> where suspending 1/2" to 1" of Pb can be a
> big engineering problem, even if you ignore the
> problem of how much load your floor
> can take.
>
> Shielding a c-arm is not a good comparison to
> shielding PET isotopes. Typical c-arm
> doses will be reduced to less than 2% by 1/32" Pb,
> but the same lead will reduce a 511
> photon dose to only about 90%.
>
> -Gary Isenhower
>
> Date sent: Fri, 20 Jun 2003 10:01:52 -0700
> (PDT)
> From: John Jacobus
> <crispy_bird@yahoo.com>
> Subject: Re: LNT and resources [Was:
> Scientific responsibility]
> To: Gary Isenhower
> <garyi@trinityphysics.com>,
> radsafe@list.vanderbilt.edu
>
> > Gary,
> > Shielding is certainly reasonable problem for a
> small
> > scale operation. At our place, I did a shielding
> > evaluation of a new C-Arm, and recommended only
> 1/32"
> > lead of one wall. The comment was, "Well, we can
> > order and use 1/16" all around." The difference
> in
> > price was too small to worry about.
> >
> > By the way, I assume you were not taking "credit"
> for
> > the concrete slab between the floors.
> >
>
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=====
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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