Re: A once in a lifetime opportinity

[brian whatcott <inet@intellisys.net>]

At 13:23 12/3/97 -0400, Ludwik wrote:

[Leigh]
> > I got 20 mCi in all, a second dose while exercising.

> Without trying to be too picky, what is a typical dose (in rems=rads)
> received by an individual?

An (approximate) estimator for dose rate from y-ray point sources is
5000 C E /d^2    roentgens/hr.

C source activity (Ci)
E energy of y-ray (MeV)
d distance from source in cm.

Using C = 10mCi
      E = 0.14 MeV
      d = 3 cm.       half radius of cardiac muscle
dose rate is estimated at 0.8 r/hr initially.


> 20 mCi of Tc99m (or 0.010 Ci)...

?

> The Tc99m atoms which were in Leigh's body several days ago turned into
> Tc99. They are no longer in his body (Tc is highly-soluble in water). 

Sugar is highly soluble in water. Nevertheless, I fear the sugar
I consumed several days ago is still with me in some form. 
It is a question of 
metabolic turnover.

> Radioactive
> decay would be linear, rather than exponential, if the average decay 
> rate were to remain constant.

Actually, the prerequisite for exponential change is to have a constant 
rate of growth or decay.

> But how can the rate be kept constant
> when the number of atoms (in the parent generation) becomes less and
> less?

Does the bank rate of 10% p.a. change if it is your $84000 or my $44 ?

Sincerely,