Re: Elimination of Background Radiation

[Wes Van Pelt <VanPeltW@idt.net>]

Dr. Mortazavi:

In 1968 I was going to do a Ph.D. thesis on this very subject, but did
one on radon daughter aerosols instead. I did a literature search and
almost started some experiments with neurospera crassa (mold).

You can reduce the background by culturing the microbes within a lead
(or steel) shield.

You must pay attention to the beta dose from natural K-40 in the medium.
Try to use low potassium growth media and low potassium glassware.

The real trick is to set up some controls at, say, normal background and
4x natural background.

The controls must be cultured the same way as the low background cells,
except for the dose. You could try to "add back" the radiation by using
a sealed source or adding some soluble beta emitter to the culture
medium.

Again, the low dose and controls must be identical except for the
radiation dose.

Also, take care that identical experimentals have essentially identical
end points when done several times. That is, you must take into
consideration the inevetible variability when doing the same biological
experiment many times and measuring some parameter.

Choose a parameter to measure which is most sensitive to the radiation
dose. That is, you may want to count the number of cells at various
points on the S-shaped growth curve. Probably the most sensitive
parameter would be the number of cells in the culture at the time of
fastest growth (i.e., at the middle of the growth curve).

Good luck.

Wes Van Pelt
-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                KF2LG
President, Van Pelt Associates, Inc.     
Consulting in radiological health and safety.
mailto:VanPeltW@IDT.net        
http://shell.idt.net/~vanpeltw/index.html


S.M.J Mortazavi M. wrote:
> 
> Dear Colleagues
> 
>   One of my students wants to do a research work about "Physiological
> benefits of background radiation" . She wants to eliminate the background
> radiation from environment of cultured microbes and cells.
>   What is the best practical method for elimination or reduction of
> background radiation. Any information appreciated.
> 
> Best Wishes
> S.M.J. Mortazavi ,Ph.D
> 
> Medical Physics Dept.
> School of Medical Sciences
> Tarbiat Moddarres University
> P.O. Box 14155-4838
> Fax (98 21) 800 6544
> Tehran , IR Iran