CATS (forwarded msg. from Carol Marcus, M.D.)

[BCOLE@AFP76.HUMC.EDU]

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Date: Mon, 13 May 1996 16:06:39 -0700 (PDT)
From: marcus@AFP76.HUMC.EDU
Subject: CATS

It is not possible to get 5 mSv external radiation from an I-131 treated 
cat with Graves' disease. You only give about 2-3 mCi to begin with.

If we assume that the cat's thyroid has a 70% uptake, an effective
thyroidal halflife of 4.3 days, a non-thyroidal iodine body clearance
halflife of 8 hrs, and we assume a 25% tandem person at 1 meter, and
assume that the specific gamma ray constant for a cat is that of an
unshielded point source, then a 3 mCi administered activity would yield
the following: 

_
D       = 34.6(0.7)(3)(4.3)(2.2)+34.6(0.3)(3)(0.33)(2.2)
0.25+pom  ______________________________________________
                              40,000

=	0.0172 + 0.0006
=	0.0178
=	0.018
=	0.02 rem	= 20 mrem
                          _______           
			  _______

The only way you can get more is to :

1)	Eat the kitty litter;
2)	Eat the cat.

Q.E.D.

Skiing in Colorado for 3 1/2 weeks a year gives you about 20 mrem extra 
of background. So does flying 20,000 miles. For this we need an NRC?


Carol Marcus