Re: LNT and resources [Was: Scientific responsibility]

["Gary Isenhower" <garyi@trinityphysics.com>]

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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